Transcript for:
Énergie et changement climatique : enjeux clés

I'm going to give you a lecture on, let's say, two objects that will accompany you throughout your personal and professional life from now on and besides also since the past, which are called energy and climate change. So I'm not an academic. My job is to be a consultant. I am a partner in a consulting firm. I have a second job as President of an association. And I do extension work that eventually led to this course. That's why I do this job rather than my main job. The course I'm going to give you is essentially a course based on observational data, relatively simple reasoning with hands. I hope it will be accessible. It is not very different (to be very frank) from a number of things that I can tell in other forums for audiences that have not been carefully selected through contests. So, normally you should be able to keep up. I'm still going to remind you of a couple of little things as an appetizer. The first is that you will remember much more easily what I say if you take notes (even if you trash them afterwards) rather than if you don't take them. So it's a very good mnemonic way to take notes. The second thing is that I will try in particular to invite you to always approach problems by reasoning by orders of magnitude and rules of 3. You have entered this school having been carefully selected for your above-average ability to solve complicated problems that are well-posed. All right? You have been selected to enter this school for solving problems that are univocal: they have only one solution. Perhaps a little complicated, but they have only one solution, and they are well-posed. That is to say, in the problem, you have all the information you need to find the solution. Life and what I'm going to tell you from now on, is essentially made up of ill-posed problems where you don't have all the information. All right? And when we approach a problem that is ill-posed and that we do not have all the information, there is something that is extremely effective in addressing these problems -- and it will be particularly true in what I am going to tell you -- it is to reason by orders of magnitude and rules of 3. And everywhere in your life, if a sophisticated model is not in line with a well-established rule of 3, it is because the model is wrong! So here are some elements that I give you as a preamble to the course that we will have the pleasure of going through together. This is one of the most famous pensioners in France. He is retired because he would have said he was going to stop working, but that must not be entirely true because from time to time, we see him do things that are less fun than that. It doesn't matter. So we're going to get him back in a little bit of service. When you ask a question in the Millionaire Game, for those of you who have already watched this excellent game, you know that you are given 4 answers in advance. That is, you are told : “Here is the student sitting there in the second row, does he have a shirt a) blue, b) green, c) yellow, d) black” and all those who were currently sleeping are failing, the others have the right answer. Now, we will imagine that he asks a question in an open way, that is, he asks you: “What is energy?” You know that in France there is a Minister of Energy so you could ask him: “What is energy?” Normally, he should know since he is the Minister of Energy. Well, you would realize, if you asked the question (I'll give you an example in a few minutes), that in fact, the first answer that comes to the bulk of the population, I mean the bulk of the population, so I'm not talking about the world in which you live on a daily basis. It's this. That is, if you say “energy” in a number of forums and in particular in a forum that we call “general public”; the first thing that will come to mind for many people -- and in fact it is normal because it is something that is also the first way to present energy in the world of economists -- is that it is something that is bought: a convenience. It's a thing to buy and so the main subject is whether it's expensive or cheap, and if we could do it differently to get the same thing for less expensive. This is particularly true in the news since for all of you who have followed this kind of movement, you know that it started with a dispute over fuel prices. So, of course, that is not the main issue at the end of the day, but it started with this dispute, which was a dispute over fuel prices. So, the Yellow Vests never said: “We don't want to consume fuel because it's too much CO2” or “We don't want to consume fuel because it makes us dependent on Russia, Norway and we don't want to.” No, no. They were just saying: “It's too expensive.” All right? So what I'm going to try to explain to you during part of the rest of this course is that, if you look at the problem from that perspective, unfortunately, you're missing the point. There are several reasons why we are missing the point. The first is that if you look in strictly economic terms what it costs to buy energy in relation to what you earn. And you can represent it in several ways. One of the ways I represent it, is to look at what it costs to buy each year from the whole economy, to buy the oil, gas and coal that made it work. So, I look at the whole economic product of the year and I look, in relation to this economic product, what it costs to buy on the market all the oil we consume in the year, all the gas we consume in the year (I speak for the world as a whole) and all the coal we consume in the year. Well, the result I get is that it costs a few percent of what we earn. A few percent of what we earn. I will show you a graph in a short while on how much it costs the French to buy energy and I assure you that to pay Free, SFR or Orange (sorry I didn't name anyone) to say: “Hello, I'm late” or “Where are you?” It costs roughly the same price. About the same price. It costs a few percent of what we earn. And from the moment an object placed in an economic debate represents a few % of the debate, well, at that moment, the normal reflex will be to say: “I will take care of it a few % of the time.” And typically, what you see right now in political debates is: I'm interested in energy at election time a few percent of the time and then, the rest of the time, I give this to someone to whom I delegate the problem by telling them: “Make sure that this thing is managed in your own corner, it's not really my problem. I do not see the link with pensions, diplomacy, economic policy or the number of printers in the country. There is no connection. So I will consider it a subject that can be detached from the rest and only requires a few percent of my time.” What I'm going to tell you from now on is that this reasoning is as relevant as if I told you: “Your brain is 2% of your weight, so I can remove it from you, it's not very serious, you'll lose 2% in efficiency.” So, “pie chart” reasoning (and that's something that's broader than just energy) “pie chart” reasonings never tell you if the “pie pieces” are enslaved to each other or not. There is another funny reasoning of the same type which is to say: “Agriculture is 2% of GDP so we don't care, we can dump it, it doesn't matter much.” Well, yes, except that if you stop eating, the remaining 98% of GDP, quite quickly, will be problematic. So, the “pie chart” reasonings, you always have to be very wary of the fact that it doesn't represent the dependence you can have on one “piece of pie” to another. And what I'm going to show you now is that, in fact, the dependence of the 97 or 98 or 95% of GDP that are not energy purchases, in fact, is totally 100% dependent in the modern world on the 5% in question. So, energy is not an invoice, even if… Well, objectively, it is not just an invoice even if that is how we reason in the economic world in which we live. There is another thought that often comes to mind when we talk about energy. It's people telling you: “Ah, energy, good energy, that's the energy we save.” So, the second thing I'm going to show you during this course is that if you're in this room right now with the time, at your choice, to sleep for those who take a nap or to listen, instead of being picking potatoes, it's precisely because the World has been increasingly consuming energy over the past two centuries. [Sorry.] So, in fact, the result of the world we live in today is a world of growing energy abundance and not at all a world of growing energy savings. So, in fact, the right energy, in the sense of the one that allowed the emergence of the industrial civilization in which we live, is precisely the one that we have not saved. The third topic that is very popular at the moment is that: “Energy is not very serious to know what it is. What is important is that it will become 100% renewable.” You will see that, in fact, that is not exactly how it happened. And, in fact, the right way to approach energy could be the poet's. That is, energy is what you are filled with on a morning when you are in good shape (or an afternoon, it depends on when you get up). Well, in fact, this way of seeing things is the right way because, when you consider that you are full of energy, in fact what it means is that you consider you have a great ability to control your destiny. “I have a lot of energy, I'm very fit”, that means, basically, “there's not much I am afraid of”, and so, “I have a great ability to control my destiny”. But energy, as we will see from now on, is that, having a lot of it, is precisely having a great ability to control your environment. It's that by definition. By definition, having a lot of energy means having a great ability to control your environment. And why is that? Because energy, before being an invoice or before being a subject of debate, is a physical quantity. So you know it well because you have done a little bit of physics to get into this amphitheatre, energy is a physical quantity. It's quite funny, moreover, because in physics there is no totally univocal definition of energy. I'll suggest one for you. For me, energy is what quantifies the change of state of a system. All right? Energy is what quantifies, I mean quantifies, calculates, the change of state of a system. In other words, the more the world around you changes, the more energy has come into play. And, the more energy that comes into play, the more the world around you changes. It's as simple as that. So if I take this back to transformations in everyday life, here are some of them, or more precisely objects that transform the environment in everyday life. These are objects that transform the temperature. These are objects that are intended to change a temperature, which I show you here. Either to heat or to cool down. And these objects use or eventually release energy. Here are some objects to change a velocity. That's all a car is for. It is used to change the speed of what is contained in the car, eventually you and your luggage when you go on holiday. Well, a speed change is a change in the state of a system. Here are some objects to change a shape. You had soil, the soil is excavated, it is placed next to the hole. Change of form. You had a sheet metal, the sheet metal is stamped and you have a car door. Change of form. These machines use energy. You have energy that comes into play when you change a chemical composition. And, by the way, the first chemical composition that constantly changes to provide energy in your immediate universe is called your digestion of the food you eat. Actually, that's what they're for. They are used to provide you with energy. You have energy that comes into play when you have magnetic fields that interact with electric currents. So, it can either consume it, in an engine, or “supply it”, in an alternator. You have energy that comes into play when you rearrange the nucleons of a nucleus. And you know the sun spends its time doing that. It is a large permanent thermonuclear bomb that spends its time assembling hydrogen nuclei to make helium nuclei. You have energy that comes into play when you have material-radiation interactions. So, the interaction of matter and radiation that interests you the most is your smartphone. But in the end, there is more to it than that in the interaction of matter and radiation. One that will be of great interest to you, and to me too in a month and a half represented by this young woman on the right. So, in a general way, using energy is nothing more than transforming the world around us and conversely, transforming the world around us necessarily implies that there is energy involved. So, once I told you that, a first small remark. Man is in transition. You know that we currently have a Ministry of Energy Transition and not just a Ministry of Energy. We have a Ministry of Energy Transition. Well, the Ministry of Energy Transition is probably the oldest Ministry in the human community, since Men have been in energy transition for 500,000 years. 500,000 years ago, the only energy that humans could use was their bodily energy. And then, they started to domesticate the fire, so a first extracorporeal energy. In Antiquity, we started to domesticate all renewable energies and, by the way, even some fossil fuels. For example, oil was known to the Sumerians, coal was known to the Chinese a few thousand years ago, so in small doses all this. And in fact, the industrial revolution was the domestication of fossil fuels, we will come back to that. And so, the energy transition is a permanent state of human beings. Every time they find a way to use a new energy source, they do it. What characterizes the modern era (and you will see that it characterizes it extremely strongly and that is what poses a problem) is that we have radically changed the order of magnitude in all these processes in a very, very short time. So energy, as I told you, is a physical quantity. From the moment I said that energy is a physical quantity, it means that there is every chance that energy will be governed by laws that we cannot change. That's the charm of the laws of physics. It's that you can understand what Maxwell's equations are, but once you understand them, you can't change them. You can't say: “Well, it would be nice for the purchasing power of consumers if we could change Maxwell's equations a little bit.” No need to try. Well, as far as energy is concerned, you have a few laws that apply to us and that cannot be changed. So, it is not to say that we do not try to change them from time to time implicitly by votes in the National Assembly, but, nevertheless, it is better to know them. So, as I told you, energy is what quantifies the transformation of the environment. The first cardinal law that is very simple to keep in mind when it comes to energy and that you all know by heart, of course, is the first principle of thermodynamics or energy conservation law. So, the energy conservation law applied to humans has a consequence that is simplistic, which is that humans can do nothing more than extract from the environment an energy that already exists and use it for their benefit. That's all Men are capable of doing. If Men were able to make energy appear within them without communicating with the outside, we would be violating the first principle of thermodynamics. So, I'm sure that in a good Harry Potter, you can do that, but in the real world it's more difficult... So, any energy we use, we have to find it in the environment. Everything. An energy that is in the environment is called “primary energy” in the jargon of energy experts. All right? So when you see the term “primary energy” passing through the statistics (which I may ask you to look at) it means that it is energy as it is found in the environment. There is another term that is very common in energy (we will come back to it in a few classes) which is the “final energy”.
The final energy is the energy that passes the final consumer's meter. So, who is the final consumer? It is you when you are at home and you have a gas meter or an electricity meter or you have an oil tank (it's very bad, you can't tell anyone) and a meter on the truck that delivers the fuel or when you are an industrial, you have a meter because you use gas in a glass furnace. There you go. So, as soon as you are an end consumer, individual or industrial and you buy energy that will allow you to operate a machine, it is called final energy. The energy found in the environment is called primary and in between, you obviously have the energy system. So historically, the only primary energies that humans know how to use are food and the warmth of the sun. There are two of them, I should have put the heat of the sun on too. So, historically, the only converter that people have at their disposal is themselves. Because, to use energy, you need a converter. We have to get this into something that will transform it. So, the only converter that people have is themselves. So, they eat, they heat themselves in the sun and from these energies that they absorb or ingest, it comes out heat, a lot, work, a little. And then, over time, we started to be able to domesticate other converters. So, apart from wood, a very rustic converter, we started to domesticate all possible renewable energies. So, at the time, renewable energies included other living organisms, because they were completely renewable. Draught animals are perfectly renewable. It eats perfectly renewable grass and therefore provides you with perfectly renewable energy. Wind and water were also domesticated through the mills. Ancient Europe was covered with water and then windmills. And so, it must be clear that renewable energies are not the future, they are the past. So not in the sense that there is nothing to expect from the future. What I mean is that renewable energies were part of our daily lives a few centuries ago. So, a world 100% renewable energy, I know very well what it looks like. I have at least one sampling point, it's the world three centuries ago. This one is 100% renewable energy, it works very well. So, a world with 1 billion people on Earth, 30-40 years of life expectancy at birth and two thirds of the population in the fields, that, I know it works in 100% renewable energy. There is no problem, since we did it once. Obviously, the debate today is: “Can we achieve civilization with the engineers at MinesParisTech and all the machines we use today with 100% renewable energy?” So, we'll come back to that later. And then, two centuries ago, there were a few brilliant engineers and physicists who said: “We could use other converters, converters that are non-renewable, in this case machines made of metal, and we will give them an energy that we do not yet know how to use on a large scale today, called fossil fuels.” So here, I summarize for you in one sheet what has been the energetic history of men. First the converter is us. Then it's other living organisms. There were slaves in it too. Then, renewable energies and, ultimately, metal machines with fossil fuels. And so, what I'm telling you also is something that's absolutely essential is that, in fact, we don't consume energy, except what you eat. So, when you see “energy consumption” somewhere, it's an inappropriate term. Because unless I'm mistaken, I don't think you've ever drunk oil. If anyone has ever done this here, let them tell me, but normally not. I don't think you've ever eaten coal except the one used for flatulence. And you didn't breathe gas, at least not methane, the one that gives Mickey's voice maybe. So, we don't consume energy with our own bodies. In fact, when we say that we consume energy, it is an inappropriate term -- but it is an inappropriate term that induces an optical illusion that is extremely strong. Consuming energy is actually domesticating a machine. So, wherever you are going to see “energy consumption”, including in my slides – because from time to time I use this shortcut even if I try not to You replace by “using machines”. And wherever you see that we are “consuming more and more energy”, you cross over and replace it with: “We are using more and more machines”. That's what you have to understand. And in fact, the increasing amount of energy we use is nothing more than how to increase proportionally the huge mechanical exoskeleton we have created for our profit. It's this, energy. And this world of machines is the world in which you live. So, unless I'm mistaken too: moral and weather conditions make you come to this class dressed. If you are dressed, it means that you have put on a piece of clothing at one time or another. So, putting on a piece of clothing takes exactly a few seconds, even if you are extremely clumsy. In the dark, badly awake, after the ingestion of substances that I will not name, perhaps a few tens of seconds but never much more. A few seconds, then. Well, in a matter of seconds you have mobilized thousands of machines for your benefit without realizing it. You have mobilized thousands of machines for your benefit. You started by mobilizing all these agricultural machines for your benefit if you have a so-called natural textile garment: cotton, linen, etc. You started by mobilizing all the agricultural machinery that sowed, harvested and eventually processed cotton for your benefit. You have, if you use a synthetic textile fiber (so everything that is poly-whatever, nylon-thing, all this comes from oil). So, if you put on an underwear that has synthetic fibers or a t-shirt that has synthetic fibers, well, you have put on a piece of oil platform plus a piece of steam cracker plus a piece of refinery, those little 5 billion-dollar beasts right there that you see in that picture. If you have something other than an unbleached fabric, it has been dyed, so it was necessary to make the dyes. So, you have the chemical industry that has worked upstream, then you have machines that have.... Sorry, we had to weave the fibers first, excuse me. So, these are mechanical machines again. It had to be dyed, so this is the chemical industry. It had to be transported because obviously it is not where you grow the cotton that you weave it, that you dye it, etc. So, you have other machines that have been involved at all the intermediate stages of the chain called trucks, trains, planes. It was necessary to manufacture boxes in which refineries were installed, in which chemical plants were installed, etc. So, you also have these machines that have come into action. It was necessary for power plants to supply part of the process. So, these machines also came into action. In short, in something totally trivial that we do as we breathe – that is called putting on a garment --, well, you don't realize it but there is an army of machines that have worked for you, just with this very simple gesture. So, after you get dressed, those who have proper hygiene will brush their teeth after breakfast. Again, it's the same: brushing your teeth is something that takes three minutes if you follow the doctor's advice, one minute if you're in a hurry. You have again used considerable quantities of machines simply to make this gesture. You have here a picture of a chemical factory in northern France that belongs to the Roquet family group and that produces a sugar that is found in toothpaste, called sorbitol. Then you know that sugar causes cavities. So, if you put sugar in your toothpaste that causes cavities, it's still a bit of a stretch. So, it turns out that the sugar we want in the toothpaste -- so that it tastes a little nice -- is a sugar that does not cause cavities. It's a different molecule and, in fact, it's one of the few hundred molecules you're going to take out of a factory called a starch factory, into which you put a full train of wagons loaded with corn every day and you take out hundreds of different chemicals. And, on site, there are a few thousand people working on a plant that runs in 3/8. It is one of the largest chemical plants in France. Then you have your tube that is made of plastic. Now there are no longer really any metal tubes. So, in plastic! New oil platform / refinery / steam cracker / etc. And your plastic tube, it does not appear by the operation of the Holy Spirit from the plastic. You need an extruder, that you see here. You brush your teeth in front of a mirror because otherwise you do stains everywhere. So, we had to make the mirror. Here you have a train-float that makes the mirror and, again, you need boxes, trucks, etc. And then you brush your teeth with purified water and this is a water purifying device, for example. So, again, an army of machines that have worked for a daily gesture called brushing their teeth. Now, I come to the most important thing in your life: your phone. Well, it's the same thing. When you make a phone call, you have mobilized an army of machines for your benefit. It was necessary to manufacture plastics for the telephone, to manufacture purified water, etc. Steel must be manufactured for antenna supports. You have 40 different metals in a smartphone. 40! Some present at extremely low concentrations and several tens. So, there are as many mining activities here and there, so there are as many mining machines, etc. Let's take the telecom network, that makes possible to operate the – because if you're the only one with a smartphone and others don't, it's not much use, you have to be able to communicate with others. So, we need a network. Here is for example a machine to run cables to make the network, etc. So, making a phone call is also something that will involve thousands of machines for all the intermediate stages of construction and operation of the device. So, I say it again. Today, we live in a world of machines and all these machines without exception use energy. All of them! And you understand well, to reverse the reasoning I showed you earlier on: It doesn’t matter if it's 3%: if you instantly deprive the world of energy, it's not 3% of GDP you're going to lose... It's quite simple to understand. You no longer have a means of transport that works. You no longer have banks, no water networks, no hospitals, no transport of any kind because no energy. All right. So, you will starve, you will freeze to death and you will kill each other. Basically, that's what happens if tomorrow morning, instantly, we deprive the world of energy. So, the whole modern world depends on it and that it costs 1% or 100% of what you earn is not so much the subject. Well, it's a subject, but it's not the only one. From now on, we will look at a number of quantitative elements. So how do we count energy? You know that when you are given an exercise to enter to MinesParisTech, generally the unit you are allowed and the only one is the Joule. I'm not going to use it much because if I expressed in Joules the quantities we're going to discuss from now on, there would be so many 0’s on the slide that you'd take too long to look at it. So often we'll use units of energy a little different from the Joules because it avoids Gigas and Megas and it allows us to have smaller things. So, already the first way to remove 6 zeros in Joules, is to switch to kilowatt-hours (kWh). And the advantage of the kilowatt-hour is that it is what appears on the bills (even if energy is not just a bill). It also brings us closer to things that are more familiar in everyday discussions. A French individual today uses, all uses included, imports included (i.e. including the energy that has been used outside France to operate the machines that supply his consumption in France – because, to take the example of your smartphone, from now on, it is “made elsewhere” in its entirety), well, it is around 60,000 kWh a year. As for energy companies, they have a unit that they also like, which still allows them to gain 4 zeros, which is the ton of oil equivalent. The ton of oil equivalent has a very simple definition: it is the equivalent of the energy released by the combustion of one ton of oil. So, a ton of oil does not always have the same combustion energy, it depends on the nature of the oil. That's why we usually add “average quality” and it's worth about 11600 kWh. From time to time, you will also have units in the energy that are brought in by the Anglo-Saxons, especially the Americans; and you know that American units are rarely compatible with the metric system. There you go. So, the ton of oil equivalent is part of that big whole. OK. I'll use a little bit of the electron-volt. Not often. And finally, I will also use the “slave equivalent”. So, the “slave equivalent” is about 100 kilowatt-hours of mechanical energy and I will explain why right now. Who has done this before in this amphitheatre? Oh, not more? Well, who has already walked up the Eiffel Tower? Well, that's better already. So, let's imagine that for some reasons that interest you, you decide to climb the Eiffel Tower 6.3 times during the day. Who has already climbed the Eiffel Tower 6.3 times? Ah, that's good. It's to impress the Japanese or... No, it's for another reason? So, if you climb the Eiffel Tower 6.3 times during the day, with the Eiffel Tower at just over 300 m, you will experience a difference in altitude of around 2000 m during the day. In doing so, you will generally use your legs since using your arms is harder... Well, the mechanical energy that you are going to release with an effort of this nature (which is not a totally marginal effort for everybody) is E = mgh. So, it's extremely simple. Well, actually, it gives a ridiculous half a kilowatt-hour over a day. So, a man at work who uses his legs to power any mechanical device like Charlton Heston who pedals in “Green Sun”, at the end of the day, he will have been able to restore or provide about half a kilowatt-hour of mechanical energy. If you imagine that this man at work makes this effort every two days. Which is another way of saying that you climb the Eiffel Tower three times every morning. Well, by the end of the year, your legs will have provided about a hundred kilowatt-hours of mechanical energy. So, over a year's work, the carcass of a reasonably trained man is capable of providing about a hundred kilowatt-hours of mechanical energy if he uses his legs. If you use your arms (and let's say by passing a little bit of back also and a shovel -- it's more difficult with bare hands), and that you pour six cubic meters of soil, that is to say about 15 tons of soil in a day, well, in addition to blisters, you will have provided 0.05 kWh of mechanical energy. That is to say, you are even “ten times more ridiculous” than the person who climbed the Eiffel Tower three times with his legs. So, a pair of arms at work during the day is 0.05 kWh, a pair of arms at work during the year is about 10 kWh of mechanical energy. If you burn a liter of petrol, that costs the scandalously high price of 1.60 € (which justifies finding it too expensive) you're going to get 10 kWh of thermal energy. And if you want to have a strict comparison, obviously you have to put it into a machine that will convert this thermal energy into mechanical energy; even with the best engineers in the world to make cars, you will get 2 to 4 kWh of mechanical energy, no more. It doesn't depend on the engineer, the 2 to 4, it actually depends on how the car functions (if it is close to its optimal performance or not). Well, so if it's 2, it's the driver's fault, it's not yours. So, you will get 2 to 4 kWh of mechanical energy. That is to say, in a single liter of petrol (which we will see in a short time that the French still consume not far from 1000 liters per year), you have the same work content, the same capacity to change environment, as in 10 to 100 days of hard work by a human being. I am telling you again when you use a machine that consumes a liter of gasoline, you are able to change the environment, that is to provide work, at the same level as 10 to 100 human beings who would use either their legs or their arms. I don't know if you realize the difference you have between the energy we use through the machine and our own body. If we convert all this into money, another way of saying the same thing is that the kWh of mechanical energy, if I pay a man at work to provide it, I will pay him from a few hundred to a few thousand euros, while the machine at work provides me the same service for a marginal cost (I did not put the machine in there) in the order of a few tens of cents. So, when I go from man to work to machine to work, outside the cost of the machine, I divided the cost of a unitary transformation of the environment by a factor of a few hundreds to a few thousands. The reason why we are mechanizing everything we can in the economic world is there. So as soon as you can replace a worker with a robot, you do it. As soon as you can replace a worker assembler on a chain with a robot, you do it. As soon as you can mechanize anything, a farmer, replace it with a tractor, you will always, always, always, always do it, because of this absolutely considerable difference in price between human labour and energy. That is why we have always been looking for effective machines to replace people with machines. It even worked for the replacement of slaves. If you take a slave, which is usually not a youthful vocation… Well, this slave, to make him work, you're going to have to go get him against his will. You have to pay money. I would remind you that there was a time when there was a slave trade that was a completely immoral business by current standards, but in the meantime, it was still done for economic reasons. You have to stop him from killing you, you have to stop him from getting out of here, you have to feed him and so on... And when you look at what it costs to get a slave's work, you realize that even that, it will cost you 10 to 100 times more than the machine that has nothing against its condition as machines, that does not seek to get out of the way and that does not go on strike and works 24h/24. So, the reason why slavery has disappeared in societies that have had access to energy is not because the genetic code has changed. So, I'm going to make a little incursion into the course you didn't go to for some of you: it's not because our genetic code has changed. Our genetic code is exactly the same as that of our ancestors two or three centuries ago. Simply, there are no longer any incentives to do things that we were doing at the time because we found much better and much less annoying to do the same thing. So, what freed the slaves was oil. At this stage, there are some initial conclusions that I propose to you. So, I remind you that using energy implies that energy already exists in the environment. So, sometimes in a debate, you see people telling you: “We could use hydrogen.” Hydrogen in the environment, there is a place where there is a lot of it, it's called the sun. It's not very convenient to pick it up. The rest, it is everywhere in bound form. In water, there is plenty of it. You have a lot of it in life, etc. But everywhere, it is in bound form, so it is not available as an energy source. The molecule is available, the energy is not. You have to break the bonds, so for example electrolyze water and for that you need more energy than the energy you get from hydrogen combustion. So, hydrogen is not a primary energy source. When you are told: “We could use the fuel cell.” Well, it's an engine. The fuel cell is not an energy source. So, what we have to compare to the primary energies we use today is other primary energies, i.e. things that can be found in the environment and that are usable as they are in the environment. The rest is not accessible. As energy quantifies transformation, you have no “green energy” (or, by the way, no “pink energy” and no “black energy”). In fact, choosing an energy means choosing a type of transformation and choosing advantages and counterparts. Any energy is dirty if you bring it to a sufficient level of use. Any one of them. The day you cover the entire planet with photovoltaic panels, it stops being clean. So, clean energy, in general, when you look at the figures, you realize that it is an energy that is used in sufficiently small quantities that its disadvantages are also small. In general, this is a clean energy. As soon as energy begins to be used in massive quantities, regardless of how it is extracted from the environment, there are disadvantages. And choosing an energy means choosing between the disadvantages you want and those you don't want. That's the point. Something that is absolutely essential, I will come back to it several times during this first module of the course, is that energy (I am not talking about what makes it possible to extract it from the environment) energy is free! So, you all heard, the wind is free, the sun is free. So, there's no reason not to use it. In fact, wind and sun are free, no one in this room has paid a penny for the sun to exist, for the wind to exist. But no one in this room paid a penny for oil to exist either! Oil is free of charge. What needs to be paid is the willingness to share of the person who is lucky enough to be sitting on it. That's what you pay for. And what needs to be paid is the work of the few of you who will go to Total (it's very bad, don't tell anyone!) to go make holes in the ground and bring out the oil. That's what you pay for. Oil is free of charge. It's free of charge. So, when we pay for energy, all we pay is human labor and human rents to access energy that is free. We only pay men and the money is used to pay only men. You've never seen nature send an invoice to anyone. So, we only pay men. As energy is physics, and as what you pay for is not energy itself but the work you have to dedicate to extract it from the environment, the price of an energy does not depend on the abundance of energy (because you could say “if the energy is very abundant, it is thus even more free than the others”). In fact, that is not what matters. If an energy is very abundant, it can still be very difficult to extract from the environment. You know, there is an energy that is totally superabundant in the universe, it's the 3 Kelvin degrees radiation in the void. I can tell you that you will never do anything with it, although there are absolutely considerable quantities. So, the fact that there are absolutely considerable amounts of energy does not tell us anything about how easy it is to extract it and use it for our benefit. What will count for the cost of energy, i.e. the ease with which it can be extracted and used for our benefit, is the fact that the pre-existing energy source in the environment is already very concentrated and with few barriers separating us from access to this source. And so, the archetype of this thing is oil. Oil is hyper-concentrated (less than nuclear energy, but nuclear energy is more complicated to use). It's very concentrated and the barriers that separate us from its access are not very hard to cross. Historically, Mr. Drake went to Titus City to make three holes and the oil spilled. It's not very complicated historically to get oil out. The more energy is separated from us by large barriers and the more diffuse it is, the more expensive it will be to extract from the environment. It's just physics. And then I'll show it to you with a quick comparison. Let's imagine that I take the volume of air in this room, which is not very far from representing a cube of 10 m on each side. Let's imagine that I blow it at 80 km/h, which is either a good mistral for the southerners, or 45 knots of wind for the sailors. And I'm running this through a wind turbine. If I put this wind through a wind turbine, it will put this wind mill in action and provide me with electricity. This electricity is an energy, I can count it. Well, the amount of electricity I recover with a thousand cubic meters of air at 80 km/h that passes through the wind turbine is the same as the amount of energy I recover by burning 3 ml of oil, 3! Not 3 tons, not 3 liters, not 30 liters: 3 milliliters, 3 mini-milliliters. With regard to the amount of human work to invest, in your opinion, is it easier to go and make a hole in the Saudi desert and bring out 3 ml of oil or is it easier to build a wind turbine, wait for the wind to blow and recover the electricity that comes out? Well, the answer is in the prices. Since money only pays men. If you use a wind turbine, in Europe, you will pay 6 to 8 cents for your kilowatt-hour of electricity (for the wind turbine part) and at that price, there is class when there is wind. When there is no wind, the video projector does not work. Well then, I can yell a little loud, there's no microphone, it's okay. I can do with my hands without a projector, but for all of you who have come by subway, there is no subway either, it's a little more annoying. There is also no party tonight if the wind is not blowing. This is starting to get really, really annoying. There's no alarm clock tomorrow morning if it runs on electricity. The fridge: you can't cool the beers, well, it's a disaster. So, if there is no wind, the system stops. If you don't want the system to stop when there is no wind, you have to add the cost of storage. And then, at that moment, you multiply roughly by 3, sometimes by 6. So, the order of magnitude of the kilowatt-hour stored with wind is a few tens of cents. In contrast, the order of magnitude of the cost per kilowatt-hour already stored (since when you take your oil out of the ground it is already a stock), at that time, you can already use it today, tomorrow, the day after tomorrow, next week, or at 3am, exactly as you wish. Well, this kilowatt-hour of oil already stored out of the Saudi desert is worth 0.3 cents. So, between the cost of one kilowatt-hour extracted and stored from the wind (diffuse source, the air is not dense: 1.2 kg per cubic meter, it's really not dense) and the cost of a kilowatt-hour coming out of a Saudi oil well you have a factor of about a hundred on the cost of making available a stored kilowatt-hour. And again, there, the wind turbine, you made it with oil. The system is not closed-looped. That is to say, to manufacture the wind turbine, you have benefited from a very efficient industrial system that has extracted the copper from the mine, extracted the bauxite from the mine, extracted the iron ore from the mine, metallurgy upstream, assembled all this stuff, transported, erected the concrete block, etc. All this was done with fossil fuels. If you had to do all this with other wind turbines, it is not completely certain that the price of the wind turbine would always be 6 to 8 cents per kilowatt-hour. We can take the bets. My bet is that it would be worth a little more. So even if you do the wind turbine with fossil fuels, you realize that you have a factor of a few tens to a hundred between a kWh out of the wind and a kWh out of an easy oil well. And that's irremediable because it's physics. So that's why historically we haven't switched from fossil fuels to renewable energy, but we have done the exact opposite. Two centuries ago the navy was 100% renewable and moreover as the wind does not always blow, it was necessary to take lemons on board to be sure that sailors did not catch scurvy. And it came to us that, to bring you the Zara t-shirt quickly (because the t-shirt is not made in France), it's still much better to have a 100% fossil navy. It's much more efficient. It goes a lot faster. We had a 100% renewable transport system a few centuries ago and we thought that, nevertheless, to supply the Ecole des Mines for lunch, it's not terrific, it's much better to have 100% fossil transport, it works better. We had a 100% renewable agriculture and we thought that, nevertheless, to have a very productive agriculture and for farmers' children to go to school, it is not terrific, it is much better to have a 100% fossil agriculture. We had 100% renewable civil engineering -- that's how the Romans built the Roman roads -- it wasn't very fast to build a million kilometers of roads in France, it's still much faster to use We had a 100% renewable construction industry. A century to build Notre-Dame. So now it's going to go a little faster to rebuild the roof. And probably a few centuries to build the pyramids: it wasn't very effective. To build Tower D2 at La Défense, it's much better to use fossil fuels, it goes much faster. We had a 100% renewable industry. Again, it wasn't very effective making all the objects you have on you, at low cost: it doesn't work well. It is still much better to have a 100% fossil industry. We had 100% renewable dryers, that is to say the sun, and it is still not very efficient: it is much better to have dryers that run on gas, it goes faster. So, it's been two centuries. Precisely because the physical characteristics of fossil fuels are superior to the physical characteristics of renewable energies, that Man, who is an accumulative animal, has spent his time switching from renewable energies to fossil fuels, to be able to accumulate faster. That's exactly why we went that way. And so, when you see that, you tell yourself that to go the other way, like that, simply because the political promise is that you will get there without touching people's standard of living, just by seeing that, you tell yourself: “Oh, yeah? Oh, yeah? Are we totally sure? Do I sign with all my savings plus those of my parents plus those of my grandparents, on the fact that it will work?” Incidentally, when you have a doubt about something, it's a very good question to ask yourself. That is: “Would I agree to bet all of my parents' savings on what I am saying?” There you go. End of the parenthesis. If you have a very slight doubt that the answer is not yes, it is because, in essence, you are not totally convinced by the argument or by what one is telling you. So, we know renewable energies very well. This is the world from which humanity comes out. So, I insist, I'm not saying we shouldn't go back. I'm just preparing you for the conclusion that we're probably not going to go back with constant consumption. Certainly not. With 7 billion people on Earth... So that's it, our converters of ancient times, they were completely immoral, and not at all effective. However, it was completely renewable. And we have now moved on to modern-day converters that are much more efficient, no doubt about it. So, if I don't talk “energy” but talk “power” now. Well, you see, a man at work whom I told you earlier in a day's work, he can do between 0.05 and 0.5 kWh. If you relate that to 5 hours of work (actually it's 10 but whatever), you see that it means that his average power over that time is somewhere between 10 and 100 W. Let's take a tractor. An ordinary tractor today has a power of a few tens of kilowatts (kW). A tractor has the same power, by the way, as a construction machine that makes a hundred kilowatts. If, one day, you're a little curious, the next time you pass by a construction site on all construction machinery, you have a small plate that gives you the power of the motor that is hidden somewhere under the pivoting part. Anyway, it's not very complicated to locate go check it out by curiosity, you will see the power of the device: a few tens of kilowatts up to 100 kW for a large shovel. If you substitute legs, a few hundred, if you substitute arms, a few thousand. So, the two machines you have here are capable of replacing a few hundred pairs of legs or a few dozen draught animals with the tractor. And, for civil engineering or construction machinery, a few thousand pairs of arms. It is thanks to this that we have been able to increase a farmer's productivity by a few hundred: because he did not grew hundreds of arms and hundreds of legs like in Shiva. The farmer was simply given an exoskeleton. And it is thanks to this that, today, we can build a house (that plus a whole lot of other machines, cement factories, trucks, etc.) that we can build a house today for the cost of a few years' salary: thing that was totally unthinkable for an inhabitant of ancient times. Until two or three centuries ago, it was just unthinkable that someone could have their house built for a few years' salary: it didn't exist. A truck pedals like a few thousand times the driver's legs. A plane, thanks to the young and handsome pilot who is well paid, pedals like a million times on the pilot's legs. The “Aeroflot” one probably didn't pedal hard enough. An industrial rolling mill hammers and crushes the steel like the whole of the Île de France to whom I would have given a hammer. So, you see. Just to replace the Fos-sur-Mer rolling mill, if we didn't have any energy, you wouldn't be listening to this course right now, you'd be hitting metal sheets with a hammer. Just to replace the rolling mill in Fos-sur-Mer. The whole of Île-de-France with a hammer, hammering all day long. This is another agricultural auxiliary that has saved a few million pairs of arms: it's called a steam cracker, and it's something that helps you prepare organic chemistry. At this point, we agree that energy quantifies transformation. On the fact that, to use energy, you actually need a converter. On the fact that most of the converters we use today are no longer our own bodies but are machines. And now I will quantify the number of machines and how they are broken down by individual. So, I told you, historically, what we were using was mainly renewable energy. So here you have a graph that starts in 1860 and quantifies only one of the renewable energies that we have used since ancient times -- because for wind and water, it is difficult to have statistics in long series. I'm sure someone would be able to reconstruct that, but I didn't find it. So now we're already going to start with the wood. So, wood, a century and a half ago, was used by humanity. Humanity uses it to feed stoves, to heat itself, to feed forges. And, by the way, the beginning of metallurgy has been a massive factor in deforestation or a very important factor in deforestation in Europe. And to operate the first steam engines that are about to emerge here and there. At that time, an inhabitant of the world, an earthling, consumes an average of 5000 kWh of wood per year. So, you see that, per person, since that time, the amount of wood used has decreased. Not in total, but per person it has decreased. It is roughly the only energy that has followed this evolution. After that, Men started using coal. So, some of the coal substituted wood. For example, in Europe, we started using coal. Before, we used charcoal and then we started using so-called “bituminous coal” (both called “coal”) to run the forges. And then to run the steam engines. And you see that the amount of coal used per person in the world that was extremely low a century and a half ago is now about 5000 kWh per person per year. What you see on this graph as well is that the amount of coal used per person in the world has never decreased since we started using coal. So, never, at any time, has coal been an energy of the past for Men. Never, at any time. And in fact, today, you unknowingly use a lot of coal through everything that is imported from countries where it is “made in coal”, starting with China. So as soon as you see something “made in China”, it is “made in coal” and it feeds your consumption, indirectly of course, of coal. Two-thirds of the coal used on Earth today are actually used by an intermediate machine in the energy system called the power plant. So, two thirds of the coal extracted on Earth are used to power a power plant. In the rest, you have a roughly 10% that feeds the metallurgy. So, they are coals very rich in carbon that are called “coke coals” and otherwise, the rest is used to operate heating networks, stoves, district heating and finally domestic heating, etc. But two thirds of it are power plants. You know that in France we have a great debate on our nuclear power plants. Remember that, today, in the world, you have between 30 and 40 times, between 30 and 40 times, the nuclear power installed in France in coal-fired power plants. In France, we have 60 GW of nuclear power, and about 2,000 GW of coal-fired power plants installed worldwide. We will come back to this at the time of the climate course, but the Paris agreement (rings a bell?) and more exactly the 2ºC objective contained in the Paris agreement assumes, for example, that all these coal-fired power plants have disappeared by the time you are my age. All right? So, three meters separate us. So, by the time you're my age, not that far away, I can assure you, all the coal-fired power plants in the world must have disappeared... We're not really there yet... Then, Men used oil. So, what you see on this graph in an absolutely spectacular way, is that oil has never replaced coal. Oil has not replaced coal. You can see that the use of oil per person is added to the use of coal per person. The reason is that oil is not used for what coal is used for, not at all. Oil is the queen energy of mobility because oil is the energy that has the best ratio of energy transported per unit volume. All right? In a liter, so a cubic decimeter, if you put something that you use for your energy supply, there is nothing better than oil. It's liquid at room temperature, so it's something that's extremely easy to store and transport. And since it is the densest per unit volume, well, in the modes of transport where you have to take your energy with you (so you are sure to be able to go where you want) it is oil that has won the battle of the modes of transport, hands down. Today, 98% of everything that rolls, flies or sails uses oil. While I remind you that, the first car in the world to have exceeded 100 km/h was an electric car. I would also remind you that the efficiency of the electric motor is four times higher, three to four times higher than the efficiency of the oil engine. So, it is not because the oil engine is intrinsically superior that it supplanted the electric motor in the competition that took place a century ago: it is because with electricity you have much more difficulty to take with you the energy that allows you to be autonomous. That's the reason. You also see here something that happened before you were born. The sudden stop, and I really mean sudden, of the amount of oil available per person on Earth. This episode, it has a rather special name in the history of energy. It's called “oil shocks”. I will come back to this at length. The oil shocks, everyone kept in mind that it is a moment when the price became very high, then it became very low again, and “next subject please, let's forget it”. In fact, we don't forget at all. This is the moment when the oil supply grew strongly and stopped growing strongly; and when the oil supply per person grew strongly and, not only stopped growing, but then began to decrease and stabilize. So, oil shocks are not just a price episode. In fact, it's the foam on the surface of the wave. The major feature of the oil shock is that it is the end of a rapidly expanding world. These are the oil shocks and we will soon come to what they mean in economic terms. The gas comes in. So, gas, bis repetita, has not replaced oil. It came to be added on top of it. Hydroelectricity comes along. Same thing, hydroelectricity was added on top of that. Then comes the nuclear, which has been added to it, and now arrive the new renewable energies (that you see there) which is THE thing that everyone is talking about. We talk about nothing but new renewable energies. Here you have, brought down to the individual, what these new renewable energies represent in the world. And, as I am, despite appearances, a nice guy, I took the nicest possible conversion convention to account for them. Because, as many of these energies are purely electrical energies (solar and wind) you have two ways to account for them. Concerning electrical energy, you have two ways of counting it in the energy balances. As historically most of the electricity has been produced by thermal modes (these are Carnot machines -- power plants -- for the most part: you burn coal, you burn gas, you burn oil, you fission uranium, etc.) it produces heat and with this heat, you operate a turbine. It's a Carnot machine. In a Carnot machine you have a maximum efficiency (1-T2/T1) and often, electricity is counted in primary equivalent i.e. we count the thermal energy that would have been necessary to make the same amount of electricity for the modes that are purely electric, hydropower in the lead, solar and wind. And that's the convention I used for this graph. Nevertheless, you can see that today, it is something that has much more space in the newspaper's pagination than it does in the actual consumption of energy in the world; and you will soon see that not only is it true in absolute terms, but unfortunately it is also true in terms of dynamics. On the other hand, another thing that is crucial when you see this graph, is that today, the amount of energy mobilized per person per year (extracorporeal energy I should specify) is about 20,000 kWh. So, on average, an earthling mobilizes 20,000 kWh per year through the enormous exoskeleton of the machine park. With the little equivalence I gave you earlier... So that's primary energy, that's thermal energy. So, in mechanical energy it would obviously be less, but in this case, you're going to replace legs, but you're also going to replace arms, so I used a rough one-for-one convention. So, I'm telling you: it's as if, basically, each earthling had 200 people at his disposal: 200 slaves who would work for him all the time. I will tell it differently: the machinery we have built up and that works for us has the same mechanical strength as if our muscle power were multiplied by 200. So, you are, I am, we are, we have become Superman for real. It's not a matter of the mind. Except that, contrary to Popeye devouring boxes of spinach and becoming super-powerful, we devour barrels of oil and become super-powerful. Well, not us, but our exoskeleton, i.e. the machines. I'll tell it again in a different way. The material production of humanity today at 7 billion people is equivalent in volume, because of the machines, to what we would have if we had 1400 billion people and no machines. Is that clear? Obviously, we cannot afford to feed 1400 billion people on Earth. So, in fact, thanks to energy and machines, we have been able to develop a productive capacity that is beyond the muscular power of our body and we spend our day using prostheses. The train that brings me here is a prosthesis. It's an extension of my legs. The car you may use, and the plane even more so, are prostheses. They're extensions of our legs. Okay, we spend our time using prostheses. Most of this energy is fossil fuel. Then why “fossil”? Simply because they are remnants of ancient life. A fossil is very simple once again. It has a definition: it's a remnant of ancient life. We will see it at the next class, coal is a remnant of plant life (ferns that grew in the Carboniferous era) and oil and gas are remnants of plankton and microalgae that lived anytime between a few million years ago and a few hundred million years ago. So, it is fossil energy by far that dominates the global supply today. And this energy, it has therefore made it possible to set in motion a growing exoskeleton that has made each of you Ironman for real. So, we all became Ironman for real. We don't have the little light shining in the center and the things in front of our eyes there, but that's exactly it. So here are some little bits of your Ironman costume and mine: washing machines, elevators, vacuum cleaners, tractors, Ariane rockets, satellites, water purifiers, rolling mills, etc. All these are little bits of your Ironman costume. And without this Ironman costume, you would have the life that French farmers had a few centuries ago with 30 years of life expectancy at birth, no increase in income between birth and death... The idea that income increases with age is something that is modern: it didn't exist in ancient times. So, what has literally changed the lives of humanity is the energy and the machinery that makes it possible to use it. That's why the fact that it's only worth 3% of what we spend is an optical illusion! It's at the center of 100% of what happens to you. 100%! In fact, with the little economic convention I showed you earlier, the energy today and the machinery it operates is 200 times the muscle power of Men. If the accounting were to be consistent with this physical reality, in companies' accounts, energy would be worth 200 times more than wages. That's what should happen. So, your hiring salary should be roughly divided by a factor of 1000. Roughly. That is about what we should do if we were to have the same accounting balance on costs as we have the physical balance on the contribution to the transformation of the world. I'll tell it another way because I'll get to it in a little while: today, people in production are only needed to operate machines. For the rest, they are useless. So most of the jobs we do today in the world, I cut off your 2 arms, your 2 legs, and I allow you to order a computer with your brain, it still works. It still works. So, this exoskeleton, with its own energy, allows it to have the same productive capacity, so on average worldwide it is 200 the factor, but on average in France it is rather 600. So, the French Yellow Vest who doesn't realize it (and that's the unspeakable political truth) still lives like a nabob. He lives like a nabob. So, what pisses him off is that Bernard Arnault lives even more like a nabob than he does (and he's probably right to think so), but in the meantime, he himself already lives like a nabob. Because of that. These modern-day slaves have another absolutely considerable advantage over the renewable energies of ancient times: it is that they free up the entire surface for us. Because the energy slaves of ancient times, either renewable energies or other living organisms that were needed, mobilized soil. A draught animal mobilizes soil. Therefore, the soil that is necessary to feed the draught animal is no longer available to feed Men or a transport animal. At the time, therefore, there was a particular need in agriculture to mobilize a large part of the land in order to be able to cultivate the rest of the land for humans, with draught animals. There, the slaves of modern times, they eat from the underground. So, they leave all the available space to us. And that is one of the reasons why, when we talk about returning to renewable energies, you see land use conflicts appear. For example, to grow crops for energy purposes, it directly conflicts with food crops. So, in fact, it means that we are obliged, for part of the energy we use, to return to the ground compared to the advantage we had of just hitting the underground. So, we are returning to a two-dimensional system, whereas we had succeeded in moving to a three-dimensional system. In a way. Some orders of magnitude of common energy usages. This thing is very old but the order of magnitude is still valid. There's probably a dividing factor of 2 that's been running around for some of them, but that's okay, it's just for fixing your ideas. What you see then, all that I can translate into “slave-days”, which I did. Above all, remember from this graph that most of the energy consumption of a Westerner, and therefore the machines he uses for his benefit, is not light and is not recyclable coffee cups. So, since I am going to talk to engineers who are supposed to manipulate orders of magnitude: it is not with small gestures that we avoid big problems. We can have small actions to start tackling the big problems, but that doesn't replace tackling the big problem. So, I say this because in the world in which I live, which is the business world, it is still very, very often that we confuse orders of magnitude, deliberately! You hide behind your little finger and say “Look! It's fabulous, I put a hive on the roof, I put recyclable cups in the canteen, and then one day per year people will come by bike and...” No, it doesn't work that way. Obviously. So here you have some orders of magnitude of energy consumptions. You see that something that will weigh very, very heavy, is what you buy and how you move around. When we talk about climate change, we will also see that the way we eat is something significant, and the way we lodge. So, basically, the size of the accommodation you occupy, the energy you use to occupy it, the amount of stuff you buy in the year and the way you travel and the number of kilometers you drive in the year, is much more impacting than turning off the light or not when you leave a room. It is not at all the same order of magnitude. So, at the same time as, per person (because until now I talked in “per person”) the orders of magnitude have fundamentally changed. The size of the population has also fundamentally changed. You have here a reconstruction (approximative obviously because ten thousand years ago INSEE was a little less efficient than today) you have an approximate reconstruction of the human population. Then why ten thousand years ago? Why does this graph start ten thousand years ago? It is the sedentarization of Men. That is, ten thousand years ago (and we'll see about that in the climate change course) we get out of the last ice age, we are at the beginning of the warm interglacial era, which is the one we knew until we started to initiate human-induced climate change. This means a period of very strong climate stability that allows people to settle down. That is to say, in a stable climate, the resource that allows you to feed yourself does not move around because it moves with the changing climate. It always stays in the same place so you can start settling down. At that time, there are a few million humans on Earth. Again, INSEE was not very successful at that time. At the beginning of the industrial revolution – I recall the life expectancy at birth of the inhabitants of Earth in 1800: it is a little less than 30 years. By the way, it was less in the city than in the countryside because at the time, cities were a place where miasmas of all kinds were concentrated and therefore as soon as there was a disease, it was much easier to catch it and die from it than when you were in the countryside. You also had the same thing for infant mortality... And there are 1 billion of us. And, what you see is that in the time frame of two centuries, we have experienced an evolution that is closer to hyperbolic than exponential, at the same time as the quantity of resources of all kinds consumed per individual has also increased. So, in fact, some of the people I know, including myself, are wondering whether this demographic change would have taken place if we had not had abundant energy. Because if we had not had abundant energy, it is not completely certain that cereal yields would have increased from 10 to 80 quintals/hectare in Ile-de-France. It is not entirely certain that food could have been transported wherever it is needed from where it grows. It is not completely certain that we would have been able to protect it from the hot, cold and all the little animals that want to eat it in our place. It is not completely certain that we could have brought drinking water and evacuated the miasmas from cities, etc. And so, there are a lot of things that are not completely certain in a world where we would not have had fossil energy, and so it is not completely certain that we would have grown to 7 or 8 billion people. And if the question arises as to whether 7 or 8 billion people is not a consequence of abundant energy, then obviously, at that moment, the corollary question arises: from the moment we enter a strong energy decline, do we stay at 8 billion people? It's not completely certain either. If I make “population times individual use” this is what I obtain regarding the total amount of energy used by Men. That is, basically, the evolution of the machinery park, knowing that between here and there it takes much less energy to run a machine, because your predecessors and mine were astute on how to run the machines, and therefore gained in efficiency. So, what you are seeing here is a lower bound of the number of machines in operation around the world. So, in my opinion, here we are close to the machinery park, and this is more like one-tenth of the machinery park in operation in the world. What you see is that, between my parents' generation and my children's generation, the amount of energy used by Men has increased by a small factor of 10 and, in my opinion, with the energy efficiency gain that there has been in the same period of time, the number of machines in operation in the world has increased by a factor of a few tens. It is not completely certain that the same thing will happen between you and your grandchildren's generation. It's even pretty certain that it's not going to happen. So, it is quite certain that the world you and I will know for the few decades that I still have to live (if all goes well) will not be a world of prolongation of the trend we have had in the past. I remind you that physical systems are exceptionally linear systems. In general, they are non-linear systems. And that, in non-linear systems, you cannot reason by induction. It is better to avoid it. If I look at the mark of Man on his environment. I can approximate it by the amount of energy he uses since, I repeat, the amount of energy we use is the flow of transformation that we operate (by the very definition of what energy is). So, for that, I take the energy per person times the population and it gives me something that looks like the evolution of the human print on its environment. Well, here is the population. I do “times energy used per person” and this is in first approximation how Man's print on his environment evolved on a planet that was 13,000 kilometers in diameter at that time, and still is 13,000 kilometers in diameter at that time. And so, you understand that the environmental problems we have today are not necessarily problems that are qualitatively different from what we had in the past. However, they are quantitatively different from what we had in the past. Today we have a tiny little problem of order of magnitude. And when you see that, you also understand that we have put the system out of balance (a tiny little bit) and that it is not completely certain that it will remain in that state for extremely long. So here I am preparing you for something that I will detail in other courses, which is: things will happen anyway in the future, and anyway, in the future, the world will not remain stable. Anyway. And, therefore, we have, you have, I essentially have a choice between: I wait for the instability to happen as it wants to happen and I suffer it; or I trigger the instability within the limits of what I can still more or less control. But it will be one or the other. Two small additions on the evolution of the amount of energy used in the world. Here you have the variation in the amount of energy used by Men between 2000 and 2017. And, what you see is that -- notwithstanding the media discourse on the fact that it's really good because we have more and more wind and solar production -- what you see here is that the 3 energies that have increased the most over the period (and by far) are the three fossil fuels, and in particular coal. So, the fossil energy that has increased the most since we started having major debates on climate change, is coal. Coal, over this period, increased more than ten times more than solar energy (in primary equivalent) and more than five times more than wind energy. So, if the newspaper had a pagination reflecting the facts, for an article about solar energy, there should be 15 about coal. All right? That's what should happen. And if you look today at what you have in terms of supply, so I'm pie charting the historical evolution I showed you just before, you see that it is fossil fuels that dominate the global supply with head and shoulders. First, oil, then coal and gas. If I just look at renewable energies, you see that what comes first is wood, followed by hydroelectricity. I would like to point out that the first two terms of France's renewable supply are the same two: wood and hydroelectricity. Just because the newspaper talks about wind and solar power, again, doesn't mean that it's what counts the most in French renewable energy supply: it is wood and hydropower by far, the other terms afterwards being much, much weaker. And so, here is the French renewable supply. A little graph I made just yesterday with statistics that were published no later than two weeks ago. What you see is that the first two terms (by far) in the French renewable supply are wood (which is mainly used for heating) and hydroelectricity (which is used to make electricity). Here you have wind and solar power. You can see that solar energy is in fact one of the weakest terms in the French renewable energy supply behind many other things, heat pumps, waste, etc. Here are all these renewable energies (so these are millions of tons of oil equivalent, I told you that I would use tons of oil equivalent) in a French consumption that is about 250 with this same unit. So, you see what renewable energies represent in this whole. Now I'll let you go for five minutes. Take the opportunity to chat a lot at that time: but five minutes, not a quarter of an hour. Thank you. I'm going to go back to prices a little bit now. You have probably (for some of you) heard (I will come back to this in the next course but I will already give a little overview today) that the price of energy (which can't be discussed in the last row of this amphitheatre) must increase sharply if energy becomes scarcer, which means that more abundant energy should see its price fall sharply. The price of all energies is in fact more or less subject to the price of oil. So here you have the oil price expressed in constant currency, i.e. in a currency adjusted for inflation over the past century and a half. So, you see something quite interesting: it is that this oil price, in fact, on a long trend, there is a century during which it was rigorously stable (expressed in constant currency) regardless of the quantity produced. You see that at the moment of the oil shock (characterized by a strong variation of the derivative, i.e. production rises rapidly and stops rising rapidly) the price rises sharply then returns more or less to its previous level, then again you have a shock where the price rises sharply and returns to something that is not very far from its previous level. So the idea that the price of oil is something that follows the abundance of supply is not confirmed by this graph that you see here. On the other hand, the real price of things -- in fact it is not the price expressed in currency, it is the price relative to the only magnitude that remains incompressible over time, which is the 24 hours of a day. In other words, the real price of anything is not the price expressed in money, it is the price expressed in minutes of working time. If you want to express a price in minutes of working time, it means that you have to relate a price to what people earn, and therefore in this case you have to relate the price of oil to what people earn, which is what you see here, that is, the GDP per person. And then, at that moment, we fall back on our feet. You see that over the past century and a half, or over the past century, the price of a barrel of oil has been divided by 15 to 20, which means that with the efficiency of machines, which has increased at the same time, the price of a kilowatt-hour of mechanical energy has been divided by 50 to 100. We find the same dividing factor as the one you have when we compare the price of an old renewable energy with the price of a modern fossil energy. We will always fall back on this dividing factor or multiplier factor of a few tens to a hundred, which also represents the passage of a human being producing with his arms and legs at 200 slave-equivalents per person. So, basically, no matter how you look at the problem, the transition from renewable civilization to fossil civilization has been the appearance of Superman or Ironman for each of us, with a multiplication by an order of magnitude of a hundred or several hundreds of our capacity for action on the environment. And of course, as a result, all the undesirable by-products of this ability to act have also been multiplied by several hundreds. So, we have removed a lot of surface area for other living things, which is why there is a loss of biodiversity. We have induced a lot of pollutions of all kinds in the environment. So, there are a whole bunch of undesirable substances that have been released in the environment as the transformation flows have increased. This is a perfectly logical consequence. If we look at a more recent period, however, here you have the price of energy in relation to what the French earn. Well, you see that the Yellow Vests may be right for their particular case. They are wrong for the population as a whole because the price of energy in relation to what people earn, as a first approximation, has almost never been as low as it is today. So, when one says: “Aaaah! the liter of gasoline at 1.50 €!” OK. Except that we forget that people's pay slips have increased proportionally and even a little faster. So, I've already said it implicitly. I will say it again more explicitly. This abundant energy allows you to sit in this amphitheatre today, and in general, has radically changed the world around us in terms of work and professions. Almost all the people you know today work in services, work in the city and work in the service sector. I mean almost everyone you know. This is a very recent situation that is the consequence of the increase in energy supply. Here you have the evolution of the number of employees in France, broken down into: farmers in green, workers in black, and service employees in blue. These three curves cover two centuries. So, I'll just digress for a moment. When you are interested in a process, the longer the series you have, the better. The best way to misinterpret a process is to have a series that is too short compared to the characteristic time scales of variation of what you are looking at. So, you have to have sufficiently long series if you want to understand something. What you see is that two centuries ago, two-thirds of the working population worked in agriculture. So, they are farmers. You also deduce one thing from that case: if two-thirds of the working population are in the fields, it is because a farmer's productivity at that time is enough to feed himself plus half a person who does something else. That's what it means. So, a farmer is feeding 1.5 people. And then you see that the number of people in agriculture is increasing slowly, slowly as well as the volume until 1850. So, what's going on at the time? At that time, you did not have a significant increase in agricultural productivity. Basically, an 1850 farmer is about as productive as an 1800 farmer, a little more but not much more. On the other hand, what is happening is that the population is increasing and therefore, forests are being cut down to increase the cultivated areas. We are deforesting in Europe, just as we are deforesting now in Latin America or Southeast Asia. Just as we have done in the United States and Russia. At all times, population growth has meant that sedentary populations have had to cut down forests to set up cultivated areas instead. That is what the Europeans do, and therefore the French, and so we cut down forests until there is not much left to cut down. That is to say, in 1850, we go through the minimum forest level. 15% of France is covered with forests, no more. Today it's 25%. And the 15% covered with forests are essentially complicated areas to cultivate, especially mountains. And then, the industry begins to develop agricultural auxiliaries that make the farmer more productive. We start to develop trait collars, we start to develop ploughs, etc. It was the beginning of the forges and industry that made it possible to multiply the number of auxiliaries for the farmer. The first combine harvester in memory was at the end of the 19th century-beginning of the 20th century. It was pulled by horses at the time, of course. And so, auxiliaries are brought to farmers to reduce the number of farmers and replace them with machines or draught animals in the fields. At that moment, of course, it frees up some people to do something else and it feeds, but not only, the growth of the workforce in other sectors. And then, after the war, this time Ironman will arrive for real. You know that Ironman is an American creation. It's Marvel's Comics. Well, it's really the Americans. In this case, the Americans are bringing the tractors and fertilizers they had started to develop back home. And we will replace human and animal workforces with much more efficient ones. That is, tractors and fertilizers. Thanks to what, as I said earlier but I will repeat it again: the cereal yield in Beauce, for example, increased by a factor of 6 and 8 between 1945 and 1975. 6 to 8! I don't know if you realize that. And at that moment, we can free up a lot of pairs of arms and legs that are in agriculture to send them elsewhere. So where do we send them somewhere else? Well, we send them into the industry. So, industry or craft is the same thing. So, in industry and crafts, we will be able, thanks to the increasing energy supply, to start up an increasing quantity of machines and each time I have a machine that starts up, I need someone to drive it. I have a car production line, I have workers working on the line. I have a jackhammer, I need a worker to operate the jackhammer. I have a crane, I need someone to operate the crane. So, more and more machines will be built and it turns out that the energy supply at that time -- we are at the glorious thirty – you have seen the speed at which oil per person is increasing. The energy supply at that time increases faster per person than the unit size of the machine. It's a horse race. And so, despite the fact that I have bigger and bigger machines, I can create more and more jobs because the flow, the machinery, basically, is increasing. The machine fleet is increasing because the unit size of the machine is increasing at a slower rate than the energy supply per person. So, I can increase the number of machines and therefore increase the number of jobs in the industry. After the oil shocks, the opposite is true. The unit size of the machine continues to increase while the energy supply per person stops increasing. At that moment, I need fewer and fewer people to drive machines that are also getting bigger and bigger and will continue to increase industrial production. Industrial production in France doubled between 1974 and 2007. So, after the oil shocks, we did not de-industrialize ourselves, we made another industry (fewer socks and more planes), but what happened was that the unit size of the machine continued to increase even though the energy supply per person stopped increasing. So, we reduced the number of employees in the industry to operate machines that were unitary larger and that together produced more. But now, what I'm looking at is the number of people, not the productive power. So, the number of people is decreasing and we also have a second category of jobs that is increasing, which are jobs that are subjected to the industry. So here too, something that is very important to keep in mind is that service jobs do not exist without physical flows. A service job as a teacher, for example. If you do not have physical flows to make a teaching building, if you do not have physical flows to bring students and the teacher to the site, so means of transport, if you do not have physical flows to make teaching materials, books in ancient times, computers today, you do not have a teaching system. Take a doctor. A doctor, if you don't have enough money to make drugs, medical equipment, imaging equipment at the hospital, the hospital itself and the transportation to run all this, you don't have doctors. If you don't have a manufactured car, you don't have a banker to do car credit, you don't have an insurer to insure cars, you don't have a driving school instructor to learn to drive and you don't have police officers to check that people are driving well. All these jobs become useless in a world in which you do not have the underlying physical flow of manufacturing cars. So, something you have to get out of your head (and besides, I'm going to show you the correlations showing that you really have to get it out of your head in a little while), is the idea that a world rich in service jobs is a dematerialized world. It's the exact opposite. A world rich in service jobs is a world in which there are a lot of flows to manage and that's why you need a lot of people to take care of it. So, service jobs increase as industrial production increases because you have to keep going, you have to manage, you have to sell, you have to provide, you have to teach, etc. And you see that there is a period where service jobs continue to increase because industrial production continues to increase while industrial jobs begin to decline. On the other hand, from 2007, when industrial production stops increasing in Europe, we are also starting to have a topic on service jobs. And you also see a new category emerge that did not exist before the oil shocks, namely the unemployed. That is to say, the energy supply per person overall no longer increasing, the labour productivity does not increase much since labour productivity is the addition of machines. Labour productivity is increasing little and existing jobs are too productive for you to give everyone a job in an economy that has stopped growing rapidly. In other words, from the oil shocks, we are entering a time when the only way to give everyone a job is to reduce people's productivity at work. And there, the equation is different according to the different countries. Some do not accept, and at that moment, they create unemployed people: France. Others accept, and at that moment, they start creating poorly paid, poorly qualified, odd jobs, part-time jobs, it is the more liberal systems: England, Germany, America, etc. But, it is one of the two possibilities that is being set up. So that's the dynamic evolution in France. Now I will show you some static or dynamic developments that corroborate what I just said. Here you have a graph in which, with the World Bank data, each point represents a country. On the x-axis, I have the amount of energy used per person, that is, the average number of machines per person in the country; and on the y-axis, I have the fraction of the active population working in agriculture. Well, you see, it's very simple. It's: “Tell me how much energy there is per person in the country and I'll tell you what fraction of the working population works in agriculture.” All right? It's very simple. Then, here is another graph that will tell you the same thing. Here, it is the evolution from 1991 to 2014 of two data in the world (so this is the world average) it's the CO2 emissions per person (here) and the fraction of the working population in agriculture. Well, you see that, the more CO2 emissions increase (which is the case when you follow the chronological order) and the more fossil energy you have per person, the fewer farmers you have in the active population. So, it's true for the world but it's true for India for example. But it's true for China. And it's true for Brazil. I have 250 countries in the database, I'm not giving them all. But it's something you see almost everywhere. So, you put energy into a country, which means that you put machines in the country, and you take farmers out of agriculture. And so you create a rural exodus. Everywhere the same. Furthermore, the increase in agricultural productivity has allowed us to increase the quantity of animals we eat, since we need more -- or more productive -- surfaces to eat animals that will themselves need to eat what grows. 80% of what grows in France is used to feed animals. This is true for meadows, it is true for all the corn except for the few corns of the brands I will not name. And that's true for half of the wheat. This is true for almost all of the soybeans grown in the world, which is one of the four major grains grown. So, roughly 80% of the cultivated land in Western countries is used to feed animals that you will eat afterwards. And, what you see here -- so there I didn't put the energy, I put the greenhouse gases, it doesn't matter. What you see is that in food-related greenhouse gas emissions, where there is meat or fish, you have a higher hydrocarbon-related portion. And what you see is that the way of History, because of the increasing energy supply, is to go from left to right. Historically, we ate cereals and onions, that's why the farmers before had stinky breaths. Cereals and onions, and then we started eating small animals. First the product of the small animals: the eggs; then the small animal itself – remember Henry IV. People need to be able to eat small animals: chicken in a pot for example. But chicken in the pot was already garbage, because it has laid eggs all its life. It's an end-of-life waste, chicken. You eat the chicken. Then we started eating broilers, then we started eating pigs, then we started eating cows. Being able to raise cows just to eat them is something that is the hallmark of a country under energy infusion. It doesn't work… And the archetype is the United States. It doesn't work in a country with a low energy supply. And, because of the productivity brought by the machines, this increasingly meaty food costs us less and less. Here you have the share of food in the household budget in the United States. So it's a long series. I took United States because it is easy to find long series on American sites. Despite the genius of French engineers, finding long series of this nature in three mouse clicks on a French site is something very difficult. I don't know why. But then, in any case, it works very well in the United States. So in the United States, what you see is that a small century ago, the household food budget is a quarter of what they earn and at the time it's essentially home catering. So, Mrs. Michu (sorry for this sexist comment, but that's reality) buys raw products from the local farmer or from the local market and makes delicacies for herself and Mr. Michu from leeks, potatoes, eggs and chickens. Today, when you go to buy food -- in fact, most of what you buy (80% of the French purchase food through supermarkets), most of what you buy is not food. The receipt at the exit of a supermarket store is the salary of a cashier, or the salary of engineers from the company that made the automatic payment terminals (it doesn't matter), it's space rental, it's warehouse salary, it's carrier salary, it's Volvo Trucks' revenues, it's Publicis' revenues, etc. I mean, it's anything but food. When you look at the raw product in what you buy, in the good cases, it is one third of the invoice. In the bad ones it's 3%. Let's take the example of an egg box. How much does it cost to buy an egg box in supermarkets? The bad ones, the non-organic ones. No, these are the organic eggs that cost 3 euros. Yes, 1.5 euros, basically. So, 1.5 euros for 6 eggs. So, since you're stronger than me at mental arithmetic, it puts the egg at? It's hard: 15 divided by 6. How many is that? That puts the egg at 25 cents. We agree with that. Do you know how much the same egg is bought off the farm? 6-7 cents. You can see that, just on an egg box -- zero processing, zero processing -- you have a factor of 4 between leaving the farm and what you pay at the cash register. So, I insist, the receipt today is anything but food. This means that when you do a series over a long period of time, you actually have a massive inhomogeneity between what you watch at the beginning of the series and what you watch at the end of the series. Because at the beginning of the series, it is really the egg as it comes out of the farmer's house bought at the market by Mrs Michu. Today it's not that at all. And outside the home it's even worse. The omelette at the local café, that's not a 1.5 euros you're going to pay for it. You're going to pay it 5 or 6 euros for 3 eggs, for 75 cents of egg. So you add a factor of 10. So, in fact, the real price of food today, it basically was divided by a factor of 20 on this time scale, the rest is service. We encounter again the dividing factor of a few tens. So it varies according to the products, thanks to the energy abundance. This abundance of energy has also brought us the means of transport. Remember (without going into detail) that the more modern a means of transport is, the higher its consumption per kilometer. So we had bicycles, we had walking, we had buses, we had trains, etc. And then, today, we have the airplane, the most energy-intensive mode of transportation per person of all those imaginable. Once we had these extremely efficient means of transportation, we also took the opportunity to do something else with them. So, just a little parenthesis. In inhomogeneities, in long series, you have another thing to see: it is that over time some objects may no longer be assigned only to their original function. Because a car today is not just a means of transport. It's also a living room on wheels. So it's your own space that you carry to the office door. And that is also something that has value and it is also an object of status. So I will also make a small aside on the inhomogeneity of the series. A car, when you compare it to something else, sometimes it's hard to know what it is compared with, and that's the last avatar of the car. This is the autonomous car “by IKEA”. Is that a car? Is this a living room on wheels? Is it a computer on wheels that transports you incidentally? What the hell is that thing? The connected autonomous car. So from time to time, you also have inhomogeneities that you have to be careful about. But to return to the primary purpose of moving: the more modern are the means, the more they consume per kilometer. What I am saying is that the car consumes less fuel than the plane, which is a more modern way. And, the car consumes more than the train which is an older thing. And more than the bus which is also older, the bus itself more than the bicycle which is older, etc. So, basically, the more modern a vehicle is, the higher its consumption per kilometer is, and in fact that's what I represent here. What you have here is a graph that gives you the amount of energy used in grams of oil equivalent. So, this, this or this is really oil per passenger-kilometer. That's what you have here. And you can see that, with time, it rises. That is to say, it is lower for the train than for the bus, lower for the bus than for the car, lower for the car than for the plane. And there you have the number of traveler-kilometers traveled in the year. So the surface gives you the amount of energy that is allocated to each mode of transport. And so here you understand that it is the road that today dominates the transport that is carried out. And I repeat, therefore, the way of History is to move from economical to less economical means, because there was more and more energy available per person. Who in this room has never flown before? Two, did I count it right or not? I would have asked the same question in 1950, I would have had to ask it the other way around, that is: “Who in this room has ever flown?” And I probably would have had two hands up. The plane is something that, today, in your socio-professional category and in your country, it is something that you use as you breathe. It's extremely recent and, by the way, when you will be about my age, it's not entirely certain that it will always be the case. It's extremely recent because it's something that requires very, very large amounts of energy. Remember that a round trip from Paris to New York is a very, very large oil bathtub. It is 400 to 500 liters of oil per person for one trip, which is about the same as the annual consumption of someone using their car. For one trip. That's a lot. So, the opening of MinesParisTech school to foreign countries (excuse me, I have to live with my time) in 2060... It is not completely out of the question that it looks more like night trains to go to Sweden than to fly to Kuala Lumpur or China. Or you will come back to the semi-sailing boat to go to China, it will take you a month, it will give you memories. And you see here the way people move, over two centuries. And you have in logarithmic scale here the number of kilometers driven per person per day and there you have the different means of transport. So, you see, the horse was the one that gave the most traveler- kilometers per day (after the walk, that is there in white) two centuries ago. So, roughly two centuries ago, the daily journey of a human being was 3 km on foot. (It wears out, it wears out...) Because two centuries ago, as you saw earlier, the ordinary human being was a peasant and therefore he went back and forth between the farm and the various places where he needed to walk to do his job. So its fields, orchards, meadows, etc. That's what he was doing during the day: 3 km. And then, moreover, he lived all his life without going a few hundred kilometers away. Then you see: the horse. Here you see the rise of the train and then you see above all the rise of the car, which has become the dominant mode of transport today. But the year when cars replaced walking as the dominant mode of transport in terms of passenger-kilometers per day was the 1950s. I was about to be born. My parents were born and well born. So my parents, who were already born at that time, were born in a world in which the dominant mode of transportation for the population as a whole was walking. Also be aware of what this means in relation to the world in which you live. We have reduced the number of farmers and, as I said earlier, we have put these farmers somewhere. So where do we conveniently make industry and then tertiary jobs? In the cities. Historically, what is a city? It is a place of exchange. When you look at the cities that were built a long time ago, they are all organized around places of exchange that are: the market place (I exchange goods), the place of worship (I exchange beliefs and moral rules) – so the Church (to speak of France) is always at the center -- the town hall or equivalent (I exchange rules of living together), the school (I exchange knowledge), etc. So, the places of exchange are at the center and geometrically, the most effective thing is a disk with everyone around it, that's where it's most compact. The disk is the most compact shape. Around places of exchange which are all placed in the center. Once you develop abundant means of production and transport, at that moment two phenomena will occur: 1) you will empty the countryside. 2) you will put people where it is most efficient to produce and then exchange production. Where is it most efficient to produce and exchange production? In the cities. It is in cities that it is more effective to do this. So you're going to put people in cities and by increasing energy, so that's what I'm getting at, you're increasing the proportion of the population that lives in cities. So that's how it works for the world as a whole. In 1960 you have a little more than 30% of the population living in the city with three tons of CO2 per person, which represents the fossil energy we use, i.e. energy itself in a first approximation. And you see that today we are at 5 tons, so we have increased the energy. This has made it possible to place almost two thirds of the population in cities. So, you see this evolution at an accelerated speed in countries that have had accelerated access to energy. There is causality because you distort the structure of employment. And because a system in which you would have left all the craftsmen, each in their own corner with intermediate transport, is much less efficient than a system in which you put 100 craftsmen together. They are called workers, in a single place that you will specialize for a production and it will become very efficient. I'll put it another way. To make cars, if you have the 12-bolt that is made in Brive and then the door that is made in Aurillac and then the door piece that is made in Bordeaux, you can't get away with it. So it's much easier to put everything together in the same place and have operations that are assembled in the same place. Then, when transport becomes more and more accessible, you can go even further in there and specialize even more on certain operations, on certain sites, since transport costs you nothing. And then you take them to other places where, in mass, you hyperspecialize on something else. That's why, for example, there is a manufacturer who assembles his truck cabins in a place other than where he paints them. And in between, you carry unpainted truck cabins. You have exactly the same evolution as you can see in China. The same for Brazil, the same for Thailand, the same for Indonesia, etc. More energy, I repeat, distorts the structure of employment in the way I mentioned earlier and the jobs that appear are most effective if you increase the size of cities. So you can increase the size of cities while spreading them out, and that's exactly what happens when you have access to abundant energy. Because, at that moment, moving in mechanized mode becomes easy and so you try to do the best of both worlds. That is, a little space for everyone, while having extremely important exchange flows. And that, you can only do that if you have plenty of energy. So in the energy-efficient city, the most compact thing is the Haussmannian. Paris is one of the densest cities in the world despite the fact that there are no very high towers. Because, when you have very high towers, you have to start leaving a little space around the towers. It is complicated to tighten the very high towers as you tighten the Haussmann buildings that are stuck together. You have no space between the buildings, they all face the street and are all stuck together. With 10-storey or 30-storey towers, it's more difficult to do that. And, on the other hand, it is the most efficient mode when you don't have a lot of energy to move around. Because you can do everything on foot or by horse cart. When you give everyone a car, you go to Los Angeles. That is to say, you keep the same urban functions of exchange by being able to put the city in 100 or 150 km in diameter with each having a car. You keep the same distances covered in one hour in a considerably more spread out urban planning. So that's why, when you look at Île-de-France for example: that's what the distance between home and work looks like, which is representative of the daily exchanges in 1975. So where it's white is that we don't cover much distance. So, in 1975, there you have a dense city. People walk to work. There you are still in the countryside, people walk to go to their fields. And then, that's how it evolves over time, and that's where we are in the early 2000s. All these people have become urban, peri-urban people whose profession has become an urban profession. They are no longer farmers. They are employees of industry, employees of services. So they have entered into this travel system that is necessary for industry and services and they use their cars because there is no public transit and there will never be one. So you are starting to have extremely long distances between home and work. By the way, where we're going to put the Grand-Paris metro is in there. So, them, it will not solve their problem at all. This abundant energy has also made it possible to increase the housing stock and it has made it possible to increase it faster than the population. In 1900, then, let's say at the time of the oil crises, the average housing in France was 77 square meters and you had a little less than three people in it. Today, you have a little more than two people per dwelling! The housing itself having become larger. So, obviously, it was energy that made it possible to do that, and therefore, energy allowed divorces in particular. Because, to divorce, you have to have 2 dwellings where you only had one. Otherwise it's not called a divorce. It's called domestic disputes, but it's not called a divorce. Divorce is a physical separation. You have to have enough to house people. And by the way, today, one of the factors putting upward pressure on housing needs in France is divorce. This is probably the first upward pressure factor. You will find what I have just told you in this little graph, which this time gives you, for a given year, the CO2 emissions per person according to the share of employment in services. And, you can see that this graph says everything except that when you increase jobs in services, emissions decrease proportionally. It tells you everything but that. This is the only thing that cannot be seen in this graph. So this is another way, this time in a dynamic way, for the world as a whole. Again, you have the share of jobs in services in 1991 and 2014 with CO2 emissions per person. And you see that the two work together. And it works together again when you look at countries taken one by one. It works very well. Another evolution that abundant energy has allowed is the increase in the flow of goods since transport has also applied to trucks. There is also something we have to get out of our brains, which is that we can dematerialize transport by replacing it with information flows. Obviously, this is not true. When you look at the concomitant evolution of information flows and transport flows, whether it is goods or people, you get exactly the same result. The two evolve together. So, today, on a macroscopic scale, to say that to circulate more information would allow us to circulate fewer people or fewer goods, that is not true. That's not how it works. Then, we can ask ourselves why it doesn't work like that, but the gross result is that it's not enough to increase the amount of information that circulates to say : “Well, the result I'm going to get is that there are fewer people moving or fewer goods moving.” Energy has therefore restructured the country. What I am presenting to you for France has been applied in all the countries that have had access to energy, all of them. You had populated countryside and not too big cities. You have moved to much larger cities and empty countryside. And the cities have spread out. And all countries have followed the same trend. The only countries that have not followed it are those that have had geographical obstacles that have opposed this development. So I'll give you an example. Switzerland has indeed expanded its cities. It didn't spread them out much. Why? Because when you have a city that is at the bottom of a valley, spreading the city out means climbing up the hillsides, and it's complicated. So they did it a little bit by putting cottages everywhere, but they didn't do it in a massive way. In particular, they did not make hypermarkets on the outskirts of the city because putting the hypermarket on terraces at the top of the city is more complicated than putting it on the outskirts of the cities. So, the countries, once again, that have not followed this evolution, it is because they have had a physical barrier that prevented them from following it. This abundant energy has also been applied to leisure activities. So leisure time has increased because, like machines produce for us, it frees us up time. So it frees up time for study. At a time when there were no machines, there were no long studies. It frees up time for retirement. At a time when there was no abundant energy, there was no pension. It frees us up time for the holidays. It frees up time for us to do nothing on weekends and it frees up time for us to work only 35 hours a week. All the free time we have gained is due to the abundant energy. So, here too, remember something that will apply not only to you but to the people you will work with and live with for the rest of your life. In a world with limited energy, it is not the increase in well-managed free time that will apply. What you see here is one of the occupations of free time, called tourism. And so, a few years ago, I did a little calculation. I didn't do the calculation again, but the order of magnitude is still the same. It gives you the greenhouse gas emissions, so again the consumption of fossil fuels, linked to the way you spend your holidays. So, in there I put in the initial displacement. Going to the holiday destination by train, car, plane. I have included the possible manufacture of the object in which you live during your holidays: the tent, the caravan. The holiday home, I considered that if we built it, I counted something, if it was the old mother-in-law we had to deal with, I didn't count anything because she already had her house built a long time ago. And then I also took into account local travel if there are any, etc. If it is a skiing holiday, I have taken into account the heating of the apartment, since skiing is generally complicated when it is very hot. It is rather cold and therefore the apartments are heated, preferably with fuel oil. So I took all these things into account. And what you see is that the most modern form of tourism (i.e. I'm going to walk around the hotel for three days by plane), is also the one that involves the greatest amount of energy consumed to afford a week's vacation. Conversely, the first one, which are the forms of leisure that appeared when paid holidays appeared; that is, people took their bicycles to go camping. Or they would take the train to go camping, that's what they did at first. Here are the forms that are the most economical in terms of fossil energy -- and therefore in terms of energy alone -- to be used. So, once again, energy abundance has distorted our lifestyles. And we owe the fact that we can benefit from this leisure offer to the fact that we are on an energy infusion, each and everyone of us. That's why Sweden has been developing, for example, in recent years (it's been in the media for a few weeks but in fact when you look at the statistics, it's a few years ago) a beginning of a decrease in the number of planes taken by Swedes that is now described by the media as “Flygskam”. So, it is because Scandinavians have a rather more developed environmental sensitivity than the rest of Europeans, which can be explained by historical and geographical reasons. We will find this again on the economic level with what it costs in terms of working hours to fly. I'm telling you again, the real price of things is the hours of working time. And what you see, is that the price expressed in hours of working time to fly has been divided by an extremely important factor in the space of a few decades. This is another way of saying that energy has become more abundant. That is to say, it is easier to pay for a full amount of it with one hour of working time. It's the same way of saying it. Energy also drives industrial machines and industrial machines will be used to make all the objects that surround you today. So, the tables on which you are leaning for some, the chairs on which you are all sitting, the clothes you are wearing, the glasses for some, the shoes, etc. All this was made by industrial machines. So, the energy drives the industrial machines. So, it is the exoskeleton that makes it possible to do everything, including scissors, cosmetics and Netflix films. But it is also used as a raw material. So you have a component in energy that is sometimes called non-energy. So you'll tell me: “The «non-energy» in energy is still a little complicated.” In fact, when you see non-energy uses of energy, particularly oil and gas, it is because it is used as a raw material for organic chemistry. All organic chemistry is based on gas and oil derivatives. So, there are Americans who have done a funny little test. They have taken out of a house all the products that contain petroleum products. Well, there's nothing left. In fact they also had to tear off the floors because there is varnish on the floors. They should have ripped the curtains off. They should have ripped off the curtain rod. They should have removed the paint. I mean, they should have taken everything off. So, oil today is not only something that drives a machine, it is also the basis of organic chemistry to produce all the products that surround us. Because you don't have (more or less) a single product that surrounds you in which you don't have oil derivatives. These objects that surround us, we have to make them. After, some of them will also use energy. Here, for example, you have the evolution of the rate of household appliances. So, I didn't find a more recent series, the equipment rates have increased considerably everywhere. But you don't have a single household today in which you don't have a fridge, washing machine, etc. You have a whole bunch of things that use energy. So industry makes things and it requires energy. And after, these objects (some of them), we will use them (up to the lawnmower, etc.). And it's also going to use energy. And you see that equipment rates are increasing roughly everywhere and all the time. I already told you, I'm telling you again: divorce is energy-consuming. Because when you divorce, you have to double the housing, so you double the energy consumption of the housing. More precisely, you increase it in proportion to the new area occupied. You need to build more homes, which uses energy. You need to furnish twice as many homes. So there are things you don't really double, but there are things you double. For example, you have twice as many beds. Everyone sleeps in a bed. You have twice as many sinks, twice as many hobs, twice as many etc. And all that, you have to make it. When there are children (this is not always the case) when there are children, they must then be brought from one home to another. This requires additional travel, sometimes quite long. As I told you earlier, a number of things that are considered normal today, so I'm repeating once again retirement, studies, etc., it's energy. When Mitterrand, in 1981, said: “Everyone must go to university” -- which was the implicit promise that afterwards everyone would have an office job it was another way of saying: “I promise you the society of infinite abundant energy”, since I showed you earlier that everyone in an office is an extremely energy-intensive society. So at the time, when Mitterrand said “Everyone must go to university”, in fact he made the implicit promise that we would be able to live in a world of machines for eternity. That is the implicit promise he made. So you see that energy is not at all detachable from a whole bunch of things even and including, the way we consider access to competence. The hospital is also very energy consuming. In France, hospitals account for about 5% of the country's carbon footprint. So as a famous comedian put it: if it is the elderly that use the most health services, all you have to do is remove the last year of life. In the meantime, it still raises the question of how long in a world of constrained energy we can continue to arbitrate in favor of people who ask for very heavy equipment when they are already very old, and therefore at the detriment of all others, including the young. That's it, so energy is everywhere. So, once I told you that, we're going to do a tiny little bit of economics. This is the planet Earth. So, the planet Earth, as Coluche used to say, is square with its eyes in the corners. No. The planet Earth is made up of resources in an anthropocentric vision. So I'm going to put it from the point of view of Men. And, from a human perspective, planet Earth is a resource. All right? This is where we live, this is our home, this is where we live, so these are resources to which we have access. These resources, I will classify them into two categories, which are on the one hand resources that are renewed on short time scales. I call them renewable. And, on the other hand, resources that do not renew themselves on short time scales, that I call non-renewable. Copper ore is definitely non-renewable. There is no large-scale transmutation on Earth that replenishes the copper ore stock. Fossil fuels are renewable if you wait a few tens of millions of years. It's not a short time scale, so I put them in non-renewable. On the other hand, grass or solar radiation is reasonably renewable on short time scales. These resources are all free and they are the result of everything that has happened since the Big Bang, all free of charge. So, since the Big Bang, proton soup and everything else, a whole bunch of processes have taken place. And today, we have Mendeleev's table and all the combinations that it offers to us on the surface of the planet. For free. All this was done for free. We get there, and we decide to have a productive activity. So, what is productive activity for Men? It is using this great horn of abundance of resources and transforming resources into something else that is more interesting than the original resource. For example, I have coarse flints: it is more interesting to have carved flints to chase after my prey. For example, I have deers: it's more interesting to have carved deer antlers to make a number of things out of them, etc. So, the productive activity of Men is just that: I use existing resources, I transform them, transformation => energy: I use energy. At the time, obviously just the one of my arms, my legs and fire. And I do something else with it. And then, over time, we will increase the energy we will seek to have at our disposal. So I repeat: 500,000 years of energy transition, which will make it possible to increase everyone's production capacity. So we extract resources faster and process them faster. As soon as non-renewable resources are extracted from the environment and transformed into something else, the stock of non-renewable resources declines. So at first, it does not decline quickly, although it would seem, for example, that on flints there may have been local shortages in the Paleolithic period. So we have been able to have, from time to time, local resource shortages. So, don't laugh because at the time they were dying. And then, over time, we also understood that there was a part of what we were transforming that we could keep to accelerate future transformation. It's called capital. So, capital is the part of production that is not consumed immediately and is reusable to increase future production. So, this is all really good. We grow and multiply. We are producing more and more, so we are emptying non-renewable stocks more and more quickly. And then, at some point, you become so productive and so numerous that you also start emptying renewable stocks. Today, we have begun to empty stocks of species that were renewable, for example. We have started to empty the stocks of forests that were renewable. We started to empty fish stocks that were renewable, and so on. We are even beginning to empty the stocks of slowly renewing soils. So we started to empty a number of stocks that were renewable. And then I said transformation, so I said energy. But I said transformation, so I also said undesirable by-products of transformation. When you transform, there is always a time when you have an unwanted by-product of the transformation. These undesirable by-products of processing have been given a name in French, it is called pollution. So pollution is all the undesirable by-products of processing, i.e. those that will have an effect that we are not looking for. And, not only are we not looking for, but they’re bothering us instead. So, basically, pollution is all about trouble. So, in more orthodox terms, it is all the products that will be introduced into the environment and will have the effect of degrading the quality of the remaining assets. That's what pollution is. In there, with this definition, you can bring in climate change, biodiversity erosion, overfishing, and so on. And so, in this case, the economy that we have set up, which I will detail in a little while, consists in counting that annual flow and considering that that is all that matters. I will explain why. So, basically, we count the moment when we transform, since transformation is Man's action and money only pays men. So, in that case, we decided that the only marker of this physical flow, of the system I am presenting to you here, is the monetary counterpart of the annual transformation flow. And this annual transformation flow, in the jargon of economists, is called GDP, it is the monetary counterpart. We might as well have had an accounting that would say: “I count «plus» what I do, «minus» what I destroy. And then, on the day the marginal value of the last car I built is less than the marginal value of the last bits of iron ore, copper ore, lithium ore, vanadium, chromium and fossil fuels I used to make this car, I stop making cars and live “happily ever after” with existing cars. ” You can see that's not what we're doing. In fact, the economic system is a system without absolute limits. Nothing in the economic system tells you: “When GDP reaches 80 trillion dollars on Earth, it stops. We made a system that is potentially infinite, which is why it is so attractive. Then why did we do it? Because, two centuries ago, when we start theorizing about economics, you have a number of people who make the following observation, they say: “Economics is the management of what is rare.” What is rare two centuries ago? It is the human factor. You have lots of species, lots of space, lots of World. The United States are just at the beginning of their colonization, Russia is huge, and so on. We don't know how far the ocean goes. No resource issues. What is rare two centuries ago is the human factor. And so, two centuries ago, economists like Mr Say, who wrote exactly what is written here, said to themselves: “At first order, I will just look at the limitation coming from Men, the rest I do not care, I do not count.” And if I consider that the resources are infinite, you agree with me that any variation in stock is zero. Delta-stock on infinity, it's always zero. So I'm going to count for zero the factors that don't come from Men. Approximation to the first order which is still the one of the economy today. So I'm going to say something that will hurt your Director of Studies who just came in. The whole economy you are taught at school is wrong when it comes to approaching the human system as a whole. When it comes to approaching trade-offs within the human system, it works. When it comes to approaching the whole of Men in their environment, it only says nonsense. That's not what it's for. So, in other words, the economics that I learned in school and that we are still learning today is that the productive system is fuelled by two factors of production, human capital and human labor, and that is enough to fill the supermarket. It doesn't take into account machines, it doesn't take into account resources. So it turns out that at the time, we could have won the battle in another way. It so happens that two centuries ago, Mr Charles Dupin, a polytechnician, therefore someone very decent, baron of his state, made a first conversion calculation in “slave-equivalents”. So, at the time, he didn't call them “slave-equivalents”, he called them “worker-equivalents”. And, Mr Dupin say: “I will look in France and Great Britain at the productive resources available to us in addition to Men [so he had understood everything about physics] and I will convert them in the equivalent of human workers. So I take the population, I make them human workers […]” and by the way, he counted children for a quarter and women for half – and we wonder if that's not where “my half ” comes from when one talks about one’s partner. No, no, I assure you. Where else would it come from “my half”? So it could be half a couple, that's another explanation. But we wonder if that's not where it's coming from. So he is taking the population and he is also taking the auxiliaries that are, at the time, boats, mills, etc. And then, Mr Dupin, he says: “If I take the population AND the auxiliaries, then it becomes normal that Great Britain, which has a population about the same size as France, already has three times more industrial production. This is normal because it is not only Men who work. There are also mills, draught animals and boats. If, at the time, we had listened to Mr Dupin and not Mr Say, it is not completely certain that we would have built the economy in the same way. It's not completely certain. And what the physicist says is: “What I have on the right is my 92 elements of Mendeleev's table arranged in a different way than what I had in the original resources. It's just that.” Do you agree with me? There is nothing but the 92 elements of Mendeleev's table in all objects of everyday life. Nothing else. Do we agree? Except we didn't find them in this form in the environment. So I found them in a form, and I transformed them. So, for that I have to find my 92 elements of Mendeleev's table, it's called resources and transform them. My transformation capacity (it is the order of magnitude calculations I showed you earlier) comes for 1 from the muscles of Men and for 200 from Ironman. That is to say, from the park of machines we have built. This is my ratio of 1 to 200 that I developed for you earlier. The capital in this story is made like everything else. That is to say, this building, which is a capital element, was made like the rest by transforming natural resources. So, this building is, like the rest, made by transforming iron ore, i.e. iron and oxygen arranged in a certain way, i.e. stones (so natural resources), i.e. paint (transformed natural resources), etc. So it's done exactly the same way, just it doesn't get destroyed when you use it. That is to say, while we are in this room, for your greatest pleasure and for mine, it does not collapse. And there you understand that it is not only Men who are a limiting factor of the system. In the modern world, energy is a limiting factor of the system. In other words, if I deprive my fleet of machines of energy, I will deprive my productive system of its production capacity even if the bankers are very friendly and even if the unemployed are ready to go to work. That is not enough in the world we live in. And if I deprive the system of resources, for example I have no fish to catch, the GDP of fishing is zero. The GDP of Léon de Bruxelles is zero. Well they have to switch from mussels and chips to steak and chips, but otherwise it is zero, and so on. So if you don't have the resources and energy, you won't have the production even if you have highly motivated workers and even if you have very friendly bankers. So historically, until now, all this has not been a limiting factor. The limiting factor is indeed Men. You have here the reconstruction of GDP since the year zero. That is, since the birth of Mr Jesus Christ. So you see that, as long as there are no significant quantities of mechanical auxiliaries, there is no growth. The population is reasonably stable at that time as well. At that time too, as a man is productive as his muscular system and no more, the most populated country in the world has the first GDP on the planet. Which is? China. Absolutely. So, China, today, is saying one thing in the concert of nations: “Listen, don't make us laugh. For two millennia, we have been the dominant economic power on the planet. So just because a century of oil has put the United States in our place does not mean that it will change our view of the world. So first we'll find our place and then we'll talk. That's about the way things are. Very few mechanical auxiliaries, very little growth. With the mass arrival of mechanical auxiliaries and fossil fuels, and bang, economic models say that we will have three percent growth for all eternity. Then don't laugh. I happen to be part of an organism called the High Council for Climate. Three weeks ago, we were presented with the National Low Carbon Strategy drawn up by some of your predecessors, whom were obliged to say that a sharp reduction, a 6 to 7-fold reduction in the amount of fossil energy we would bring in France, would increase the French GDP. It's in there, it's in there. Because business models tell you that. Because economic models can tell you that we increase GDP by dividing energy by 10 since energy is not an input. There is no problem, no problem. So in the meantime, that's not what's happening. I present to you the best macroeconomic model in the world, called a straight line. Here you have in abscissa the quantity of energy used by Men, i.e. I repeat, the number of machines in service. And so, in ordinates, the economic value of the production. Which follows in a more or less linear fashion. Very simple. Really very simple. This is valid in absolute value, it is also valid in variation. Here you have in green the annual variation in the amount of energy used on Earth, i.e. the annual variation in the number of machines in service, and in blue, the annual variation in human economic production. You see that: give me one, I give you the other; and give me the other, I give you the one. All right, I'll tell you again in a different way. Euros only measure a flow in monetary terms, which kilowatt-hours physically measure. So, it's two units of account that look at the same thing, that is, a transformation flow. I come back to my curve that I showed you earlier about energy supply per person and I will make another comment this time. You can see that over the period up to the oil crisis, the energy supply increases by 2.5% per year per person. This means that the number of machines per person is increasing by at least 2.5% per year. You have a little bit of energy efficiency added. This means that as long as you do not have limiting factors on the resources to be processed, the physical production per person increases by at least 2.5% per year. And so, the monetary counterpart of this production increases by at least 2.5% per year. Actually, you'll see, it's a little more. After the oil shocks, you can see that the pace is slowing down. So in fact, it is totally slowing down for the OECD countries, which are called the rich countries, the western countries; and the surplus you have there is the rise of China, and then later of the other emerging countries. And that translates into a rise in the quantity of coal per person, which is an average effect. In fact, in Western countries, the amount of coal used is not increasing, even decreasing slightly. However, it is exploding in China. And today, China uses half of the coal consumed in the world. At this point, the system starts to slow down a little. That is, we continue to have an increase in physical production per person, but much lower, and much lower than the rate of redistribution to which we had become accustomed during that period. That is to say, in all the Western countries of the world, a welfare state has been organized, more or less. More or less. Less welfare in the United States, more welfare among the Scandinavians. But in all countries of the world, a welfare state is organized that redistributes part of what is produced and the growth rate of redistribution is in line with the growth rate of production, i.e. a few percent per year. And we do not put in the system the capacity to correct it quickly if growth slows down. In other words, we don't tell public agents: “Well, we warn you, if growth runs out of steam, increased wages with seniority, it stops.” We don't tell retirees: “We warn you, if the rate of growth slows down, you will automatically retire later and be paid less.” Etc. We're not saying that whole thing. We say: “No, no, if growth slows down, we continue to pay you the same and we increase your wages with seniority in the same way.” At that moment, you have to find the money somewhere and you get into debt. In all Western countries, public debt was non-existent before the oil shocks. It appears and develops… well very weak before the oil shocks. It appears and develops everywhere. So, it is not only the French politicians which are incompetent. It appears and develops everywhere in all Western countries after the oil shocks precisely for this reason. Because the rate of increase in production per person is no longer sufficient to ensure the rate of increase in redistribution per person. And starting from 2005 -- and I will tell you why in the next few months -- the per capita energy supply is beginning to become more or less constant again in the world. In fact, it is declining in the OECD area, I will show you right after. And then the system goes to hell: massive financial crisis of Lehman Brothers which is a consequence of what I'm telling you (I'll show you in a little while chronologically) and not a cause. Debt begins to explode. We come to something that has been unknown for a very long time called negative interest rates, etc. And that is the system's response to the fact that we built something that depended on energy abundance, and that this energy abundance is slowly starting -- slowly starting -- to fray. And by the time you're my age, we're going to accelerate in that direction. So that's why your future won't be a continuation of the past. So, a few curves to finish. You have here the variation in GDP per person in the world, and therefore the variation of economic output per person in the world since 1960. You see it here in terms of annual variation. And then I put in orange the averages over three periods: until the oil crisis, between the oil crisis 79 and the oil crisis of 2007-2008, and since the shock of 2007-2008. There is a small artifact that I'm not going to talk about today because it's too long, but debt is something that makes it possible to make GDP without production. It's a little complicated, but here you're starting to have a side effect. What you see is that: in the era of the Glorious Thirty, energy grew strongly per person, and production per person grew even more strongly, because there was a gain in energy efficiency in between. Engineers know how to make a more efficient car, which advances with less oil if it is the same car, or a larger car sold more expensive with the same amount of oil. After that, you see that the energy per person is increasing less quickly (it is actually 1% rather than 0.5%) and you see that the GDP per person is starting to grow less quickly. And since the episode... Well it's very contrasted there, you also see that there's a big episode of volatility. You can see it's dropping. In fact, you have two regions in the world that are evolving in a very discriminated way from that moment on: the OECD and the rest; and I will show to you where we live, that is, the OECD. So the OECD: this is how a first piece of the OECD evolves, i.e. the European Union in which we live. Until the oil shocks, the energy supply per person increases sharply. Between the oil shocks and 2006 -- and you see that the maximum is in 2006, two years before Lehman Brothers. So it was not Lehman Brothers that caused the economic crisis that caused a fall of the amount of energy used. It was the contraction of the energy supply that slowed GDP and made it impossible for borrowers to repay the debt they had started to incur when the economy first slowed down here. It's a two-triggers-gun. There, we start to get into debt to compensate for the fact that the energy stops increasing, and there, at the moment when the energy starts to decrease, we no longer even have the capacity to get back into debt at the right speed to repay the Ponzi scheme we had started creating. There you see an effect of the thing I will tell you about next time, which is the replenishment of the world energy market with source rock oil and gas in the United States, and oil in particular. What you see in Europe at that time is: the GDP per person is rising sharply at the time of the Glorious Thirty; energy per person is stopping growing but GDP per person is still rising; and you see that ever since 2006, the increase has been almost zero. And, by the way, Europe's industrial production today is still lower than it was in 2007. Ton-kilometers by truck today in Europe are lower than they were in 2007. The construction index today in Europe is lower than it was in 2007. So part of the increase in GDP that we have had since 2007 is false GDP. It is an accounting artifact that is basically a bad correction of inflation, if I say it differently. So, at that moment you ask British people: “Are you happy?” British say “No”. I would remind you that a referendum, in general, you answer the person who asks the question, you do not answer the question. De Gaulle learned it at his own expense and besides, you remember the result of the first referendum in France on the European Union... So, of course, we rephrased the question in a different way. But so, historically, a referendum is still a very good way to answer to the person who asks the question and not the question itself. So the English say to the person asking the question: “We are not happy with the way things are going.” By the way, as soon as the GDP per person no longer increases and you create a space of free movement in an area where you have a difference of 1 to 5 between what people in the East earn and what people in the West earn, what do you think is happening? It balances out. So when you're in an expanding universe, it doesn't matter. Because you can increase people's incomes on one side while you continue to increase or at least you don't decrease people's incomes on the other side. So, when Spain and Portugal join the European Union at a time of strong growth, the purchasing power of the French can continue to increase at the same time as the purchasing power of the Spanish increases significantly. But when you bring in 2005 (that is to say two years or a year before the maximum European energy level) the Eastern European countries by telling them: “Come and dance, your GDP will increase at the same time as ours will continue to increase.” And then, crack, the energy per person starts to drop. At that moment the GDP of the area no longer increases, your effect of connected vessels applies, and all that the Eastern countries will take, it is the Western countries that will lose it. It's mechanical. Then, there are two ways to lose it. The Polish plumber comes to London and it gives you that result. And the second way to lose it is Renault investing in Romania, and at that moment, you have the French workers yelling. And these are the two ways in which the rebalancing process applies. This is just the beginning. As long as we stay, I'm not playing politics with two pennies in my hand, but I'm just saying that as long as we stay in a space where everyone moves and pays as they please, when you have differences in initial potential that you can't homogenize from the top, you're going to have rebalances with loss for a number of people. So the temptation for Frexit, Italexit, Espaxit and Swedexit will increase. All these pressures will increase because of this. And, originally, you find energy. When you do a trend analysis, you note, by the way, that this variation in energy supply per person is in fact the result of a very strong trend (and I will come back to it in the next course) that has been expressing itself for decades. Here you have a curve that gives you the variation of the European Union's energy supply. So it's not its supply, it's its variation over the past 50 years. What you see is that the variation with large gaps follows a trend where it is strong, a little less strong, a little less strong, a little less strong, and at some point, we enter into negative territory and, by the way, at that moment, we start to have something that is reasonably volatile. If we say that this second derivative has good reasons to be representative of the internal dynamics of the process, then you tell yourself: “Well, the rest of the story is that energy supply will continue to decline and therefore the GDP growth rate, which was increasingly low over the same period, will continue to decline and move into permanently negative territory.” So the life that awaits you and me for the next few decades, if everything goes well, is likely to be nothing like what I have known since I was born. That is to say, it will not be a world of expansion, it will be a world of contraction. So we're going to need your creative genius because I assure you that managing a shrinking world is much more challenging as a constrained optimization exercise than managing an expanding world. So, we're really going to need you. We also need me, but we're really going to need you... In the sense that we're really going to need the best selected brains in the country to tackle one of the toughest problems we will have to solve, which is to keep the system more or less stable in a context of shrinking available resources. I can assure you that what you saw in the written and oral part of the contest was an easy part compared to that. I take the OECD area as a whole and I'm going to end up with that. Same motive, same punishment. The supply per person increases until 79, peaks in 2006 -- and this is also true in the United States. In the United States, the energy supply per person went through a maximum two years before Lehman Brothers, I insist. And, you also have this evolution that actually reflects a trend evolution that has taken place for a very long time, and therefore it will probably happen about the same thing in that area and then in the world as a whole. There you go. So, what I told you during this first module is that the world in which we live has been enabled notably by -- not only by -- but notably by the fact that we have found free “pockets of sunlight” under our feet, as Yann Arthus Bertrand puts it very nicely, that is to say fossil energy. Free, with a very high calorific value -- so a very high exothermic capacity -- that allowed us to transform at an accelerated rate all the other resources (also free) that we found on Earth, and it has enabled us to build the socio-economic system in which you grew up, that is, most of the people in the city, most of the people in service activities, everyone eating steak at every meal, people with a lot of free time and the demands of the MEDEF and the CGT that can be met without any problem. That's the world we grew up in. And, by the way, MinesParisTech's international exchange program since you need planes for that. And, the way I count the transformation flow is a way that is unlimited by construction, since the only thing that was really annoying in the deal, that is the fact that the Earth is 13,000 kilometers in diameter and not 14,000 and not 1,5000, I ignored it, I put it under the rug. And, on the basis of this axiom, which is only an approximation to the first order, I have refined my visions for two centuries but without questioning a fundamental axiom which is: Nature is free. So, obviously, I don't see that limit because it's not in the system. In the next course, we will not look at that, which is one of the first limiting factors of the system, i.e. pollution, and we will focus on a very specific pollution called climate change. So climate change is only the downstream consequence of this transformation flow. At the next course, what we will really look at, is the bottleneck that can eventually apply upstream of the system, and which is called the supply of fossil fuels. Obviously, if we had the time, we could look at the supply of metals, this is another possible limiting factor for the system. Species supply is another possible limiting factor of the system, etc. But then, we will look at and discuss the upstream supply of fossil fuels, i.e. of transformation capacity. So that's the picture we're going to be in for the next course I'm going to give you. Have a good evening.